LI NI UPht trin kinh t, x hi gn lin vi vic ng dng my tnh nh mt cng c cc k hiu qu v cn thit. Gio trnh H qun tr c s d liu Access c bin son nhm phc v cho nhu cu tm hiu ng dng my tnh trong hc tp v cng vic. Microsoft Access l mt chng trnh ca b ng dng vn phng Microsoft Office chy trn mi trng Windows, l phn mm thuc h Qun tr C S D Liu Quan H gip qun l, bo tr v khai thc s liu, lu tr thng tin d liu bn ngoi vo my tnh di dng cc bng v c th tnh ton, x l d liu bn trong cc bng lu tr trn my tnh. Gio trnh c bin son theo chng trnh chi tit c hi ng chuyn mn ca trng Cao ng Ngh Ph Yn ph duyt, ni dung trnh by trong gio trnh gm cc kin thc c bn sau: Bi 1: Tng quan v h qun tr CSDL Microsoft Access 2002 Gii thiu h qun tr c s d liu Access v cc thao tc c bn trn ca s Access. c bit tp trung vo nhng kin thc c bn gip c th xy dng CSDL Access mt cch chc chn; c bit th hin qua qui trnh xy dng mt CSDL tng kt c ni dung ton b chng hc. Bi 2: Xy dng bng (TABLE) Trnh by cc khi nim v bng, cch to lp bng, cc thnh phn trn bng v cch thao tc vi d liu trn bng. Bi 3: Truy vn d liu (Query) Tp trung vo cc kin thc v k nng gip x l d liu mt cch a dng thng qua cc loi Query. Bi 4: Xy dng Form Gii thiu form, cch thit k form v thit lp cc thuc tnh trn form. Bi 5: Bo biu (Report) Gii thiu report, cch to ra cc report, vn dng report v cch thc thi report. Bi 6: Macro Gii thiu macro, cc thuc tnh v s kin thng dng trong macro. Hu ht ni dung trnh by trong gio trnh u c nhng bi tp thc hnh c th. Do vy, sau khi c xong v hnh theo trnh t cun sch ny, bn c gn nh c th thit k v xy dng c nhng ng dng v qun l thng tin. i tng chnh ca gio trnh l sinh vin, hc sinh chuyn CNTT cng nh khng chuyn CNTT c hc mn Access. Tt nhin cng hon ton ph hp cho nhng ai quan tm hc hi mn hc ny bi l cc ni dung u c trnh by rt trc quan, c th t v kt qu r rng. D c gng bin son k vi mong mun h tr bn c tip cn mt phn mm tin tin, bn cnh cng nhn c rt nhiu kin gp qu bu ca cc ng nghip, song chc chn gio trnh ny khng trnh khi nhng s st. Rt mong nhn c kin ng gp ca bn c. Cui cng xin chc cc bn thnh cng trong cng vic xy dng cc ng dng tin hc trong cng tc qun l. TP. Tuy Ha, thng 8 nm 2009

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Bi 1. TNG QUAN C S D LIU ACCESSI/. PHN TCH THIT K H THNG C S D LIU 1. Khi nim v c s d liuCSDL la mot he thong e quan ly cac thong tin co cac ac iem sau: La mot tap hp (co the la rat ln) cac d lieu co cau truc c lu tren cac thiet b tr tin (nh a t, bang t , a quang) c cac chng trnh ng dung cu the nao o khai thac thong tin: tm kiem, sa oi, bo sung, xoa. Thong tin phai bao am tnh nhat quan. Co the thoa man ong thi cho nhieu ngi s dung vi nhng muc ch khac nhau. V d: Trng co lu tr danh sach sinh vien cac lp tren may tnh. Cung luc ban giam hieu can xem xet cac sinh vien e khen thng phong tai vu can lap danh sach phat hoc bong cho sinh vien. Nh vay danh sach sinh vien c ca ban giam hieu va phong tai vu khai thac cung mot luc, d nhien thong tin ve sinh vien phai nhat quan ngha la du au - ban giam hieu hay phong tai vu - thong tin ay la phai nh nhau.

P. ao Tao P. Tai Vu CSDL

P. Hanh Chnh Cac VP Khoa

P. Tuyen Sinh

BGH

Ex:S o minh hoa CSDL dung chung

2. Thc th & quan h:a) Cac khai niem: - Thc the la mot s vat cu the hay tru tng trong the gii khach quan. V du: + Trong mot trng hoc co cac thc the: giao vien, hoc sinh, mon hoc + Trong mot th vien co cac thc the: sach, loai sach, nha xuat ban 2

+ Trong mot cong ty buon ban cho phep tra cham co cac thc the: mat hang (cu the), cong n (tru tng). - Cac thc the nay co cac tnh chat rieng cua no goi la thuoc tnh. V du: Moi hoc sinh co mot ho ten, vay ho ten la thuoc tnh. - Moi thc the co mot thuoc tnh dung e phan biet gia cac oi tng cua thc the o goi la thuoc tnh khoa hay goi tat la khoa. V du: Moi Sinh vien co mot ma so duy nhat e phan biet vi Sinh vien khac. - Gia cac thc the co the co moi lien he vi nhau goi la quan he (relation). b) Cac quan he: Quan he mot mot (one to one): k hieu (1,1), la quan he hnh thanh khi mot oi tng cua thc the nay co quan he duy nhat vi mot oi tng cua thc the kia. V du: Mot nhan vien ch thuoc ve mot phong ban duy nhat. Quan he mot nhieu (one to many): ky hieu (1,n), la quan he hnh thanh khi mot oi tng cua thc the nay co quan he vi nhieu oi tng cua thc the kia. V du: Mot Lp co nhieu sinh vien theo hoc hoac Mot sinh vien hoc nhieu mon hoc khac nhau. Ngoai ra, trong thc te, mot oi tng cua thc the nay lai co quan he vi nhieu oi tng cua thc the kia va ngc lai. Quan he nay c goi la quan he nhieu-nhieu (many to many), k hieu la (n, n). V du: Trong mot th vien, ta xet quan he gia thc the sach va thc the oc gia: Mot cuon sach co the c nhieu oc gia mn va ong thi mot oc gia co the mn nhieu cuon sach.(luc nay, trong Access, ta phai bieu dien quan he nhieunhieu noi tren bang hai quan he mot-nhieu). c. Mo hnh CSDL quan he: Theo mo hnh nay th cac d lieu, thong tin ve mot thc the can quan tr se c lu vao may tnh di dang cac bang (Table). Gia cac bang co the co quan he vi nhau va moi quan he nay cung c bieu dien di dang bang V du: Xet hoat ong cua mot th vien. D lieu can quan l cua th vien gom co: * Sach ta goi Sach la mot thc the. * oc gia ta goi oc gia la mot thc the. Bieu dien cac thc the di dang bang nh sau: Sach: MaSach TenSach TacGia 3 NamXB NhaXB SoLuong

CT003

Lenin tap

toan V. I. Lenin

1980

S that

12

oc Gia MaDG DG0001 TenDG Tran Th Luyn DiaChi 11 Le Lai TP Nha Trang

Gia thc the Sach va thc the ocgia co quan he mn tra, bieu dien nh sau:

Mn MaDG DG0001

MaSach CT003

NgayMuon 1/5/2008

NgayTra 20/5/2009

II. GII THIU MICROSOFT ACCESS

1. Gii thiu Microsoft Access - Microsoft Access l mt H qun tr c s d liu trn mi trng Windows ca hng phn mm Microsoft c a vo b phn mm kh ph bin hin nay l Microsoft office. Microsoft Access c xy dng trn m hnh quan h do Codd xut nm 1970 trong di tng chnh l nhng quan h (bng-Table). - Microsoft Access cho php s dng cc cng c cho php ngi dng lin kt cc ng dng ca mnh 1 cch thun tin, chnh xc m khng cn tn nhiu cng sc cho cng vic lp trnh. Cc ng dng c bn c th thit k hon ton bng cng c v ch cn lp trnh cho nhng cng vic phc tp, yu cu tnh mm do. 2. Khi ng v thot khi Access 2002 2.1. Khi ng Access 2002 C khi ng Access theo nhiu cch: - M lnh Start | Programs | Microsoft Access 2002 ca Window; - Hoc c th nhn kp chut ln tn tp c phn m rng .MDB vi biu tng ca Microsoft Access Sau khi ra lnh chy chng trnh Access, thng thng mn hnh tip theo xut hin cho php chn cch lm vic: - Chn Blank Access database bt u to mt tp Access mi (to mi tp);

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- Hoc Access database wizard, page, and project to mt CSDL theo mu c sn (khng trnh by trong gio trnh ny); - Hoc Open an existing file m tp Access tn ti lm vic tip. 2.2. Thot khi ACCESS Chn File/Exit hoc nhn t hp phm ALT+F4. 3. Cc thao tc trn tp tin c s d liu Access 3.1. To mt tp tin CSDL bt u to mt tp mi, chn mc Blank Access database ca s trn, tip theo nhn OK, hp thoi sau xut hin:

Chn th mc trn a, ni s lu tp Access

G tn tp cn lu

Trong mc Save in: Chn th mc cn cha tn tp tin. File name: Chn tn tp tin cn to (Phn m rng mc nh l MDB) Nhap chon nut lenh 3.2. Mi trng lm vic ca Access Sau khi mt tp Access c m, mi trng lm vic trn Access xut hin vi nhng thnh phn nh sau:

2

5

1

(1) - h thng thc n (menu) v cc thanh cng c (Toolbar)- ni thc hin cc lnh khi cn; (2) - Ca s tp Access ang lm vic bao gm 7 phn chnh: Tables, Queries, Forms, Reports, Pages, Macros v Modules. Chng ta s ln lt hc cch lm vic trn tng phn ny trong cc chng tip theo. 3.3. M mt tp tin CSDL tn ti trn a Mi tp Access phi to mi duy nht mt ln, c m ra lm vic v ghi li trong nhng ln tip theo. m mt tp Access tn ti lm vic, lm nh sau: Bc 1: T mi trng Access gi thc n: File | Open (hoc nhn nt Open trn thanh cng c), hp thoi Open xut hin:

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Bc 2: Tm n tp Access cn m trn hp thoi Open bng cch: - Tm n th mc ni cha tp Access cn m hp Look in; - Tip theo chn tp Access cn m trn danh sch v nhn nt Open hoc Enter; n y ca mn hnh lm vic Access vi tp va m xut hin tip tc lm vic. 3.4. Thot khi Access Sau khi a m va lam viec vi tap tin CSDL Access, neu muon ong tap tin nay, ta thc hien nh sau: ong va lu tat ca cac oi tng ang m(v du nh bang, van tin, bieu mau, bao cao). - M thc n File | Exit; - Nhn t hp phm nng Alt + F4; - Hoc s dng nt Close trn ca s Access ang m; 3.5. Cc thnh phn c bn ca mt tp tin CSDL ACCESS Mt tp tin CSDL ACCESS gm c 6 thnh phn c bn sau: Bng (Tables) : L ni cha d liu. Truy vn (Queries): Truy vn thng tin da trn mt hoc nhiu bng. Biu mu (Forms): Cc biu mu dng nhp d liu hoc hin th d liu. Bo co (Reports): Dng in n. Pages (Trang): To trang d liu. Macros (Tp lnh): Thc hin cc tp lnh. Modules (n th): Dng lp trnh Access Basic.

4. Cch s dng ca s Database Nh ni trn, mt CSDL ca Access cha trong n 7 i tng ch khng n thun l bng d liu. Sau khi to mi mt CSDL hoc m mt CSDL c sn Access s hin th mt ca s Database, trn hin th tn ca CSDL ang m v lit k 7 i tng m n qun l, mi lp i tng u c phn lp r rng tin theo di. 4.1. To mt i tng mi 7

Trong ca s Database, chn tab cha i tng cn to (Bng, Truy vn, Biu mu, Bo co,...) hoc thc hin lnh: View/D atabase Object -Table/Query/Form/ReportPages/Macros/Modules Chn nt New. 4.2. Thc hin mt i tng trong CSDL Trong ca s Database, chn tab cn thc hin. Ca s Database lit k tn cc i tng c sn, chn tn i tng cn m. Chn nt Open (i vi Bng, Truy vn, Biu mu, Trang) hoc Preview (i vi Bo biu) hoc Run (i vi Macro v Module). 4.3. Sa i mt i tng c sn trong CSDL Trong ca s Database, chn tab cn thc hin. Ca s Database lit k tn cc i tng c sn, chn tn i tng cn m, Chn nt Design.

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Bi 2.

BNG D LIU(TABLE)

Table l thnh phn c bn v quan trng nht ca CSDL trong MS-Access. Dng ghi nhn cc d liu c s, cc nghip v pht sinh, cc bin ng v cc thng tin mun qun l. Mt bng d liu trn Access bao gm cc thnh phn: Tn bng, cc trng d liu, trng kho, tp hp cc thuc tnh cn thit cho mi trng d liu v tp hp cc bn ghi.

I/. THIT K C S D LIU

Mt CSDL c thit k tt cho php ngi s dng truy cp nhanh chng n nhng thng tin cn tham kho, gip tit kim c thi gian truy xut thng tin. Mt CSDL thit k tt gip ngi s dng rt ra c nhng kt qu nhanh chng v chnh xc hn. thit k mt CSDL tt chng ta phi hiu cch m mt H QTCSDL qun tr cc CSDL nh th no. MS Access hay bt k mt H QTCSDL no c th cung cp cc thng tin cho chng ta mt cch chnh xc v hiu qu nu chng c cung cp y mi d kin v nhiu i tng khc nhau lu tr trong cc bng d liu. V d ta cn mt bng cha thng tin v l lch ca cn b, mt bng khc cha cc ti nguyn cu khoa hc ca cc cn b... Khi bt tay thit k CSDL, chng ta phi xc nh v phn tch cc thng tin mun lu tr thnh cc i tng ring r, sau bo cho H QTCSDL bit cc i tng lin quan vi nhau nh th no. Da vo cc quan h m H QTCSDL c th lin kt cc i tng v rt ra cc s liu tng hp cn thit. Qui trnh xy dng CSDL Access n y chng ti c th khuyn co mt qui trnh tt xy dng mt CSDL Access theo thit k sn c : Bc 1 : Ln lt xy dng cu trc tng bng d liu trong CSDL. Vi mi bng d liu khi khai bo cu trc cn gii quyt cc cng vic sau : - Khai bo danh sch cc trng ca bng ct Field Name; - Chn kiu d liu ph hp cho cc trng ct Data Type; - Thit lp trng kho cho bng; - Thit lp mt s khc cn thit cho cc trng nh : Field Size, Format, Input Mark, Requried, Validate Rule, - Ghi tn bng; Bc 2 : Ln lt thit lp thuc tnh LOOKUP cho cc trng mt cch ph hp. Mi quan h trn bng thit k s cn mt thao tc thit lp thuc tnh LOOKUP (s dng trnh LookUp Wizard) t trng trn bng quan h nhiu sang trng bng quan h mt; Bc 3 : Thit lp cc thuc tnh m bo ton vn d liu cn thit cho cc quan h ti ca s Relationships (menu Tool | Relationships.. hoc nhn nt trn thanh cng c); Bc 4 : Thc hin nhp d liu cho cc bng nu cn; Ch : Bng c quan h 1 phi c nhp d liu trc bng c quan h nhiu. 9

II/. CC KHI NIM V BNG

1. Cc khi nim Bng l ni cha d liu v mt i tng thng tin no nh SINH VIN, HA N,... Mi hng trong bng gi l mt bn ghi (record) cha cc ni dung ring ca i tng . Mi bn ghi ca mt bng u c chung cu trc, tc l cc trng (field). V d: Cho bng di y qun l l lch khoa hc cn b trong trng i hc, c cc trng MACB (M cn b), TRINHDOVH (Trnh vn ha), CHUYENMON (Chuyn mn),... Trong mt CSDL c th cha nhiu bng, thng mi bng lu tr nhiu thng tin (d liu) v mt i tng thng tin no , mi mt thng tin u c nhng kiu c trng ring, m vi Access n s c th thnh nhng kiu d liu ca cc trng. Mt bng d liu trn Access bao gm cc thnh phn: Tn bng, cc trng d liu, trng kho, tp hp cc thuc tnh cn thit cho mi trng d liu v tp hp cc bn ghi. M t mt bng d liu trong trng thi Datasheet (nhp, xem, s d liu):

M t mt bng d liu trong trng thi Design view (ang thit k cu trc):

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Bn ghi c bit cui cng gi l EOF

Mi ct l mt trng d liu(Field) Mi dng l mt bn ghi (Record)

Trng kha (Primary key)

Tp hp cc thuc tnh ca trng d liu

Tn bng Mi bng c mt tn gi. Tn bng thng c t sau khi to xong cu trc ca bng. Khng nn s dng du cch (Space), cc k t c bit hoc ch ting Vit c du trong tn bng. Trng d liu (Field) Mi ct d liu ca bng s tng ng vi mt trng d liu. Mi trng d liu s c mt tn gi v tp hp cc thuc tnh miu t trng d liu v d nh: kiu d liu, trng kho, ln, nh dng, .. Mi trng d liu phi c nh kiu d liu. Trong Access, trng d liu c th nhn mt trong cc kiu d liu sau:

TT 1 2 3 4 5 6 7 8 9

Kiu d liu Number

ln

Lu tr..

Autonumb er Text Yes/No Date/Time Currentcy Memo Hyperlink OLE

Tu thuc kiu c th 4 bytes tu thuc di xu 1 bytes 8 bytes Sing tu thuc gi tr tu thuc di xu tu thuc d liu

S: s thc, s nguyn theo nhiu kiu S nguyn t ng c nh s . Xu k t Kiu logic Lu tr ngy, gi Lu tr d liu km k hiu tin t kiu ghi nh Lu tr cc siu lin kt (hyperlink) m thanh, hnh nh, ho, (Objects)

Khng nn s dng du cch (Space), cc k t c bit hoc ch ting Vit c du trong tn trng. Bn ghi (Record)

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Mi dng d liu ca bng c gi mt bn ghi. Mi bng c mt con tr bn ghi. Con tr bn ghi ang nm bn ghi no, ngi dng c th sa c d liu bn ghi . c bit, bn ghi trng cui cng ca mi bng c gi EOF. Kho chnh (Primary key) * Kho chnh ca bng l 1 hay nhiu trng xc nh duy nht 1 bng ghi. Cc mu tin trong 1 bng khng trng nhau trn kha chnh. Kho chnh c th ch 01 trng, cng c th c to t tp hp nhiu trng (gi b trng kho). V d: C cc bn d liu sau: - bng THISINH ca CSDL thi tuyn sinh, trng kho l SoBaoDanh. V mi th sinh c th nhiu trng c gi tr ht nhau, nhng SoBaoDanh th duy nht. - bng CANBO trng MaCanBo s l trng kha v khng th tn ti 2 cn b no trong bng ny trng MaCanBo - bng HANGBAN ca CSDL Qun l bn hng, 2 trng hangID v hoadonID l mt b trng kho. V khng th trn mt ho n bng hng no c bn mt mt hng no ghi lp li 2 ln. * ngha ca kha chnh: - Khi quy nh kha chnh, Access s t ng to cc ch mc trn cc ch mc trn cc thuc tnh ca kha chnh. - T ng kim tra s trng nhau trn kha ca cc mu tin khi nhp d liu. - Dng kha chnh to lin kt gia cc bng. * t kha chnh: - Chn cc thuc tnh dng lm kha(dng phm Shift hoc Ctlr v dng chut chn) - Nhp chut vo menu Edit/Primary Key * Xa kha chnh: - Nhp chut vo menu View/Indexes xut hin ca s Indexes - Chn cc trng cn xa ri bm phm Delete. * Ch : Khi to cu trc cho bng, nu khng quy nh kha chnh th khi lu cu trc bng Access s xut hin cu hi:

Nu chn Yes th Access s t ng to 1 trng tn ID kiu Counter lm kha chnh cho bng. Trng hp chn No th bng va to s khng c kha chnh. 2. Lin kt cc bng d liu Lin kt cc bng d liu l mt k thut trong thit k CSDL quan h. Chng l mi lin kt gia 2 bng vi nhau theo thit k cho trc m bo c mc ch lu tr d liu cho ng dng. Trong Access tn ti 2 kiu lin kt: lin kt 1-1 v lin kt 1-n (mtnhiu) 12

Lin kt 1-1 l: mi bn ghi ca bng ny s lin kt vi duy nht ti mt bn ghi ca bng kia v ngc li; V d lin kt 1-1:

M t d liu 2 bng ny nh sau:

Lin kt 1-n l: mi trng ca bng 1 s c th lin kt vi mt hoc nhiu bn ghi ca bng nhiu (n). Ngc li, mi bn ghi ca bng nhiu s lin kt ti duy nht 1 trng ca bng 1. V d lin kt 1-n:

C th tham kho mi cha c th c nhiu con qua 2 bng sau:

Hoc xem theo mt kiu khc:

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III/. T TO LP BNG1. Cc bc t to lp bng thit k cu trc mt bng d liu trn CSDL Access, chng ta phi tun th cc bc theo minh ha sau. Minh ho ny hng dn cch to cu trc bng HANG bao gm cc trng hangID, tenhang, donvi, dongia. Bc 1: Khi ng trnh thit k cu trc bng ch Design View. th Tables, nhn nt New, chn Design View, nhn OK.

Hoc nhn k cu trc mt bng xut hin:

trn th Tables. Hp thoi thit

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Bc 2: Khai bo danh sch tn cc trng ca bng: bng cch g danh sch tn cc trng ln ct Field Name ca ca s thit k. Ch : tn trng khng nn cha du cch (space), ch ting Vit c du. Sau khi g vo danh sch tn cc trng ca bng HANG, hp thoi thit k s c dng:

Bc 3: Khai bo kiu d liu cho cc trng ca bng, bng cch chn kiu d liu cho tng trng ct Data Type tng ng. Sau khi chn xong kiu d liu cho cc trng, hp thoi thit k s c dng: 15

chn kiu d liu, c th dng chut chn kiu d liu t hp th; mt khc cng c th nhn k t u tin ca kiu d liu cn chn mi khi nh v n Data Type cn lm vic. V d:

Bc 4: Thit lp trng kho cho bng (nhng bng khng c trng kho c th b qua bc ny). - Chn cc trng mun thit lp kho bng cch: dng chut kt hp gi phm Shift nh du u dng cc trng mun thit lp kho; - M thc n Edit | Primary key thit lp thuc tnh kho cho cc trng va chn. Cng c th ra lnh ny bng cch nhn nt Primary key trn thanh cng c; Sau khi thit lp kho, nhng trng kho s c biu tng nh sau: Biu tng ca trng kho

16

Bc 5: Lu li cu trc bng. Nhn t hp phm Alt + S hoc nhn nt Save trn thanh cng c, hp thoai yu cu ghi tn cho bng xut hin:

Hy g tn bng v nhn OK. Mi trng d liu c khai bo trong ca s trn u c th thit lp c rt nhiu cc thuc tnh tu thuc kiu d liu trng nhn. Cc thuc tnh ny c th thit lp ti phn Tp hp cc thuc tnh ca cc trng nh trnh by trn. Di y l danh sch mt s cc thuc tnh hay c s dng. Thuc tnh Field size thit lp kch thc d liu. Ch p dng cho cc trng c kiu d liu Number v Text. i vi cc trng kiu s, Field size cho bit trng nhn gi tr loi s no.

i vi cc trng kiu Text, thuc tnh ny cho bit chiu di ti a ca xu k t. V d: Vi trng Hoten th Field size khong 30. Thuc tnh Format thit lp nh dng d liu khi hin th. Trng ny p dng cho hu ht cc kiu d liu tr ra kiu: Memo, OLE, Yes/No Thuc tnh Input Mark Thit lp mt n nhp d liu cho cc trng. Kiu ny c th p dng cho cc loi trng kiu Text, Number, Datetime, Currency. Thuc tnh Default Value 17

thit lp gi tr ngm nh cho trng mi khi ra lnh thm mi mt bn ghi. V d: Trng s lng mi khi thm mt bn ghi mi, gi tr trng ny t ng l 1. Khi phi thit lp thuc tnh Default Value ca trng ny l 1. Thuc tnh Caption Thit lp tiu ct m trng hin th. Tn trng khng nn cha du cch v ch Vit c du, nhng Caption ca cc trng th nn g bng ting Vit c du sao cho d c v nhn bit. c bit gi tr thuc tnh Caption nu c s c s dng lm tiu cho cc trng tng ng mi khi s dng cng c Form Wizard hay Report Wizard sau ny- s rt tin li. Thuc tnh Validation Rule Thit lp iu kin kim tra tnh ng n ca d liu khi c nhp vo. V d: trng NgaySinh ca hc sinh phi nhp vo nhng ngy >= 1/1/1980 chng hn. Khi thuc tnh Validation Rule ca trng Ngaysinh hy g vo >=#1/1/1980# Thuc tnh Required yu cu phi nhp d liu cho trng ny (nu thit lp Yes) khi bt u mt bn ghi mi hoc khng nu thit lp No. 2. Thit lp quan h Mt bc quan trng trong xy dng CSDL Access l thit lp quan h cc bng trong CSDL. Lm c iu ny bn s gp c rt nhiu thun li trong qu trnh s dng cc trnh Wizard v Design View trong Access sau ny. Di y s l hng dn cch thit lp quan h cho mt cp bng. Tng t bn phi thit lp ton b cc quan h c th trn CSDL. Bc 1: M ca s thit lp quan h bi thc n: Tools | Relationship.. Bc 2: a cc bng (Tables) tham gia thit lp quan h thng qua hp thoi Show Tables (nu cha thy hp thoi ny dng thc n Relationship | Show table):

Cch a cc bng ln ca s thit lp quan h (Database) nh sau: - Chn bng cn tham gia thit lp quan h (thng th chn tt c) ; 18

- Nhn nt Add; - Chn xong ton b nhn Close ng ca s; Bc 3: Thc hin to kt ni gia tng cp bng theo thit k, cch lm nh sau: Dng chut ko (Drag) trng cn lin kt ca bng ny (v d trng hangID ca bng HANG) th (Drop) ln trng cn lin kt n ca bng kia (v d trng hangID ca bng HANGBAN). Khi hp thoi Edit Relationships xut hin:

Trong trng hp mun thit lp cc thuc tnh m bo ton vn d liu (Enforce Referential Integrity) cho quan h hy thc hin chn (checked) 3 mc chn sau: ng thit lp cc thuc tnh m boton vn d liu; m bo ton vn d liu khi xo d liu gia 2 bng lin quan. Khi , nu mt bn ghi bng c quan h 1 b xo, ton b cc bn ghi c quan h vi bn ghi hin ti s c t ng xo bng c quan h nhiu (nu xo 1 CHA, ton b cc con ca cha s t ng b xo khi bng CON); m bo ton vn d liu khi cp nht d liu gia 2 bng lin quan. Khi , nu gi tr trng kho lin kt bng 1 b thay i, ton b gi tr trng kho lin kt bng nhiu cng b thay i theo. Hp Relationship Type: cho bit kiu quan h gia 2 bng ang thit lp: - One To One Kiu 1-1 - One To Many Kiu 1- - Indeterminate Khng xc nh c kiu lin kt Tu thuc vo kiu kho ca cc trng tham gia lin kt m Access t xc nh ra c kiu lin kt gia 2 bng. Di y l mt s kiu lin kt c Access t ng xc nh:

19

Ch : - Khi hp Relationships Type ch Indeterminate c ngha l quan h ang thit lp khng ng v cu trc kho ca 2 bng (quan h sai); - Trong trng hp thit lp cc thuc tnh m bo ton vn d liu nu gp phi hp thoi thng bo li:

Li ny do mt s d liu ang tn ti trong bng quan h khng tho mn vi bng quan h 1. Hiu n gin l: c mt s mt hng khai bo trong bng HANGBAN cha c trong trong danh mc hng (bng HANG) nh vy l khng hp l, khng tho mn cc iu kin v ton vn d liu gia 2 bng ny. - Gp phi li sau y khi kt ni gia 2 bng:

-

Tc l 2 trng tham gia kt ni khng cng kiu d liu. V d: mt trng kiuNumber, trng kia kiu Text; hoc mt trng kiu Text, trng kia kiu Date/Time - u b sai v khng cng kiu d liu. 3. Nhp d liu Nhp d liu l yu cu bt buc i vi bt k mt ng dng no. D liu c th c nhp vo CSDL bng nhiu con ng khc nhau. Trong phn ny s trnh by cch nhp d liu t bn phm vo trc tip cc bng d liu trong Access. 3.1 Cch nhp d liu C 2 bc c th nhp trc tip d liu vo bng: 20

Bc 1: M bng nhp d liu bng cch: nhn p chut ln tn bng cn nhp d liu; hoc chn bng cn nhp d liu ri nhn nt Open; Bc 2: Thc hin nhp d liu vo bng ang m bng bn phm.

Ch : Mt s li c th xy ra khi nhp d liu Li th nht:

Li do: Bn nhp vo gi tr khng tng thch vi kiu d liu ca trng ch nh. V d: Trng kiu Numeric m g vo ch ci; hoc khng g y cc gi tr ngy, thng, nm cho trng kiu Date/Time,.. li ny s xut hin. Khc phc: hy nhp li cho ng, gi tr cc trng yu cu n khi khng xut hin thng bo li. Li th 2:

Li do: Bn khng nhp gi tr hoc trng gi tr trng kho. l trng kho lun yu cu phi nhp d liu cho mi bn ghi. Khc phc: phi nhp y gi tr cho trng kho. Li th 3:

21

Li do: Gi tr trng kho trng nhau. Gi tr trng kho va nhp vo trng vi gi tr ca mt bn ghi no trn bng d liu. Khc phc: nhp li gi tr trng kho khc sao cho va ng, v khng b trng kho. Li th 4:

Li do: Bn ghi va nhp d liu b trng trng bt buc nhp d liu (nhng trng c thit lp thuc tnh Required=Yes) Khc phc: Phi nhp d liu cho cc trng bt buc phi nhp d liu. Li th 5:

L do: Li do thc hin mt thao tc vi phm cc nguyn tc m bo ton vn d liu. V d: Bn nhp d liu trn mt bng c quan h m bn ghi ang nhp khng th lin kt c ti c mt bn ghi no ca bng c quan h 1 vi n (nhp mt hng bn m m hng cha c trong bng danh mc hng ho). Khc phc: Tm v nhp cho ng gi tr theo bng quan h 1 tng ng. Tham kho cch khc phc li ny mc 5: thuc tnh LookUp. 3.2 Mt s thao tc x l d liu trn bng ng trc mt bng d liu, c rt nhiu thao tc cn x l, v d: sp xp bng, tm kim cc bn ghi, xo bn ghi no , Ni dung phn ny trnh by cch s dng mt s thao tc . a. Xo bn ghi Xo bn ghi l thao tc xo b mt s bn ghi ra khi bng. Vi bng d liu ang m c th thc hin 2 bc sau xo cc bn ghi: Bc 1: Chn nhng bn ghi cn xo. C th chn mt hoc nhiu bn ghi bng cch dng chut nh du u dng nhng bn ghi cn chn; Bc 2: Ra lnh xo bng cch: m thc n Edit | Delete Record hoc nhn nt Delete Record trn thanh cng c hoc nhn phi chut ln vng chn, tip theo nhn Delete Record. Mt hp thoi xut hin bn khng nh mt ln na vic xo d liu: 22

- Chn Yes ng xo; - Nhn No hu lnh xo. b. Sp xp d liu Sp xp l vic thay i th t hin th mt bng d liu theo mt trt t no . Kt qu ca vic sp xp gip ngi dng c th quan st c tt hn d liu trn bng, tt nhin mun quan st bng d liu theo trng no phi thc hin sp xp bng theo d liu trng y. Cch sp xp d liu trn bng ang m nh sau: Bc 1: t con tr ln trng (ct) mun sp xp; Bc 2: Nhn nt lnh sp xp trn thanh cng c: - sp xp tng dn hoc - sp xp gim dn. Bn s thu c kt qu nh mong mun. c. Lc d liu Lc d liu l vic lc ra nhng bn ghi trn bng c cng mt s gi tr. Kt qu vic lc d liu s gip ngi dng lm vic mt cch hiu qu trn tp hp cc bn ghi h mong mun. Mt v d v tnh hiu qu ca vic lc d liu: Sp n ngy Quc t Ph n 8-3. C quan quyt nh thng mi ch em 100,000. c ct thng trn bng cng danh sch tt c cn b c quan, lm sao c th nhp vo gi tr ct thng cho ch em (khng nhp cho nam gii) l nhanh nht. Nu c ln m xem ai l n ri nhp 100,000 cho ct thng s l rt lu. Nu lm theo cch sau: Bc 1: Lc ra danh sch l cc cn b n; Bc 2: Nhp 100,000 cho tt c cc bn ghi lc. Nh vy chc chn nhng cn b ang hin th (sau khi lc) u l ch em ph n, khng b xt ai m cng khng nhm mt ngi nam no c lt vo danh sch thng! Cc bc lc d liu trn mt bng ang m nh sau: Bc 1: Nhn phi chut ln trng cn lc d liu. Mt menu xut hin: Bc 2: Thit lp iu kin lc trn trng ang chn. C rt nhiu cch xc nh iu kin lc: - Nu mun lc nhng bn ghi c cng gi tr ca bn ghi ang chn hy chn mc ; - Mun lc nhng bn ghi tho mn iu kin no , hy g iu kin ln mc: V d: 23

+ G >=10 - lc ra nhng bn ghi c gi tr trng ang thit lp lc ln hn hoc bng 10; + G 3 - lc ra nhng bn ghi c gi tr trng ang lc khc 3, + c bit: gi tr trng, rng c miu t l Null; + Lc ra nhng ngi tn Nam g nh sau Like '*Nam'; + Lc ra gi tr trong khong 10 n 15 g nh sau: Between 10 And 15 (tham kho ton t Like v Between chng sau- Queries). Mun hu ch t lc, nhn phi chut ln bng d liu v chn mc: 4. Thuc tnh LOOKUP Qua cch nhp d liu cho bng c quan h nhiu trn CSDL ta thy vic nhp d liu cho trng tham gia lin kt ca bng nhiu i hi phi c chnh xc vi d liu trn bng quan h 1 (phi nh m nhp). Trong thc t vi nhng danh mc ln n hng trm, thm ch nhiu hn na th vic nh m nhp d liu qu l kh khn: hoc g sai m, nguy him hn g ng nhng nhm m. Thuc tnh LOOKUP s gip gii quyt phn no vic kh khn trong nhp d liu trn cc bng quan h nhiu nh vy. Thuc tnh LOOKUP c thit lp ti trng tham gia lin kt trn bng c quan h nhiu sang trng tham gia lin kt ca bng c quan h 1. V d: Vi CSDL Qun l bn hng th: - trng khachID ca bng HOADON phi thit lp thuc tnh LOOKUP sang trng khachID ca bng KHACH; - trng hangID ca bng HANGBAN phi thit lp thuc tnh LOOKUP sang trng hangID ca bng HANG; - trng hoadonID ca bng HANGBAN phi thit lp thuc tnh LOOKUP sang trng hoadonID ca bng HOADON. Thng thng, ng vi mi quan h 1- c thit k cn phi thit lp thuc tnh LOOKUP cho trng tham gia lin kt t bng quan h 1 sang trng tham gia lin kt ca bng quan h nhiu. Mt trong cc cch thit lp thuc tnh ny n gin nht l trnh LookUp Wizard ca

Access. Di y l v d v thit lp thuc tnh LOOKUP cho trng khachID ca bng HOADON sang trng khachID ca bngKHACH trong CSDL qun l bn hng: Bc 1: M bng c trng cn thit lp LOOKUP ra (bng HOADON) ch Design View bng cch: chn tn bng, nhn nt Design; Bc 2: Kch hot trnh LookUp Wizard bng cch: Ti ct Data Type ca trng cn thit lp thuc tnh LOOKUP (trng khachID), chn mc Lookup Wizard.. t danh sch th xung:

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Hp thoi Lookup Wizard xut hin:

Hp thoi ny hi D liu a vo danh sch chn ly t u? Trong trng hp ny danh sch d liu chn ly t bng KHACH, nn chn mc I want the lookup column to look up the values in a table or query. Nhn Next tip tc: Bc 3: Chn d liu cho danh sch:

25

Hp thoi trn tr li cu hi: Bng (query) no cha d liu cn a vo danh sch?. Trong trng hp ny ly d liu t bng KHACH nn mc View chn Tables; v chn bng KHACH. Chn xong nhn Next, hp thoi sau xut hin:

Hp thoi ny tr li cu hi: Gi tr nhng trng no ca bng (query) chn s c hin th trn danh sch? Hy dng cc nt >, >>, >)

Cc ct c trong bng mi

i tn ct

28

Bc 3: Xc nh kha chnh cho bng v t tn cho bng va to.

Access t to kha Chng ta t to kha

Bc 4: Chn ct s lm kha chnh trong danh sch cc ct chn ca bng( trong trng hp chng ta t to kha chnh cho bng)

Chn ct lm kha chnh

(2 )

(1 ) (3 )

Trong kiu d liu ca kha chnh s l: (1): S t ng do Access tng ln khi nhp mi mt dng v s ny khng th quay ngc li( chnh l kiu d liu AutoNumber). (2): S s cho php ngi s dng nhp vo khi thm mi 1 dng d liu. (3): Chui k t cho php ngi s dng nhp vo khi thm mi mt dng d liu.

29

Bc 5: To lp cc mi quan h t bng mi va to n cc bng to trc (nu tht s c tn ti cc mi quan h ny) bng cch chn nt Relationships.

Bc 6: Chn kt qu cui cng sau khi to bng s l:

(1 )

(2 )

(3 )

(1): M bng va to ch tht k. (2): M bng ch n hin th v cho php ngi s dng nhp d liu trc tip vo bng va to. (3): To thm mt biu mu n gin dng hin th v cp nht d liu cho bng va to. Vi trnh thng minh chng ta c th to nhanh mt bng tuy nhin chng ta khng th thay i trc tip vo cc c trng bn trong ca cc ct nh rng, nh dng, gi tr mc nh,.. trong sut cc bc ca trnh thng minh ang thc hin (tt c cc c trng ny do Access nh 30

ngha trc), m ch kt thc xong qu trnh to mi ri sau chng ta mi c th thay i cc t trng bng cch m bng ch thit k ( Design View).

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III/. Lm vic vi d liu dng Datasheet

Mun xem thng tin trong mt bng chng ta phi chuyn bng sang mt ch hin th khc gi l Datasheet. Trong ch hin th ny, mi bn ghi c th hin trn mt hng ngang, hng u tin l cc tn trng. Sau y l cc cch chuyn sang ch hin th Datasheet: Trong ca s Database ca CSDL ang m, nhp chn tab Table. Trong mc ny chn bng cn hin th ri chn nt Open, bng s c m b sung v chnh sa d liu. Ta c th chuyn sang ch Datasheet ngay khi ang trong ch Design, bng cch nhp chn nt th bng s chuyn sang ch Datasheet, quay tr v ch Design, ta nhp chn li nt . Hoc chn lnh View - /Design View. 1. B sung bn ghi cho bng Sau khi hon thnh cng vic thit k cu trc bng, ta tin hnh nhp d liu, tc l b sung cc bn ghi, cho bng. Hin th bng ch hin th Datasheet, mi hng i din cho mt bn ghi. 2. B sung bn ghi mi cho CSDL ang ng ti mt bn ghi no (khng phi l bn ghi mi), chn nt trn thanh cng c. Hoc thc hin lnh Record - Go To - New. 3. Di chuyn gia cc bn ghi Ta c th di chuyn qua li gi cc bn ghi bng cch dng cng c Chn la bn ghi (Record Selector). 4. Nhp d liu cho bn ghi Khi ang nhp d liu cho mt bn ghi no , th u hng ca bn ghi xut hin biu tng

Theo chun, khi nhp d liu th Access s ly font mc nh l MS San Serif, iu ny c th gip cho ta hin th c ting Vit ch khi MS San Serif l ca VietWare hoc ca ABC. khng ph thuc vo iu ny, ta nn chn font trc khi tin hnh nhp d liu. Trong ch hin th Datasheet, thc hin lnh Format Font... Khi nhp d liu l trng cho trng OLE Object, ta thc hin nh sau: Lnh Edit - Object... 5. Chn cc bn ghi nh du chn bn ghi: Chn Edit/Select Record: chn bn ghi hin hnh Chn Edit/ Select all Record: chn ton b 6. Xa bn ghi Chn cc bn ghi cn xa, sau thc hin lnh Edit - Delete (hoc nhn phm DELETE) . 32

1. Xy dng CSDL Qun l lng cn b mt c quan c cu trc nh sau :

Bi tp

Yu cu : - Thit k cu trc cc bng mt cch ph hp : kiu d liu cc trng; trng kho; thuc tnh Lookup v cc thuc tnh khc; - Thit lp quan h cng cc thuc tnh m bo ton vn d liu cho cc quan h; - Nhp d liu nh sau : + 4 phng ban; + 5 loi chc v; + 20 h s cn b. 2. Xy dng CSDL Qun l vic bn hng cho mt ca hng c cu trc nh sau :

Yu cu : - Thit k cu trc cc bng mt cch ph hp : kiu d liu cc trng; trng kho; thuc tnh Lookup v cc thuc tnh khc; - Thit lp quan h cng cc thuc tnh m bo ton vn d liu cho cc quan h; - Nhp d liu nh sau : + 5 khch hng; + 15 danh mc hng ho c bn; + lp 10 ho n bn hng; + vi 25 lt hng ho c bn ra.

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Bi 2 TRUY VN D LIUQuey l cng c ca Access c dng truy vn d liu trn mt hay nhiu Tabl. Query cng c dng nh mt ngun d liu khc cho cc cng c khc nh Form, Report, hay Query khc. C rt nhiu dng yu cu x l d liu nh: trch - lc - hin th d liu; tng hp - thng k; thm - bt - cp nht d liu; V vy s tn ti mt s loi Query tng ng gii quyt cc yu cu x l d liu trn. Bn cht ca Query l cc cu lnh SQL (Structured Queries Laguagengn ng truy vn d liu c cu trc)- mt ngn ng truy vn d liu c dng kh ph bin trn hu ht cc h qun tr CSDL hin nay. Vic thit k mt query l gin tip to ra mt cu lnh x l d liu SQL. Vic thi hnh query chnh l vic thi hnh cu lnh SQL to ra.

I/. Cc loi truy vn trong Access

1. Selct Query (Chn lc) S dng kh ph bin trch d liu t 1 hay nhiu Table. Ngoi ra cn c th cho php tnh ton, lc v kt nhm. 2. TOTAL queries Tng hp l php x l d liu kh ph bin. Trong Access, query l mt trong nhng cng c x l kh tt vic ny. Total query l mt in hnh. 3. CrossTab Query (Tham kho cho) Dng tng hp d liu theo chng loi. Loi ny hu hiu trong vic phn tch d liu. 4. Action Query (Hnh ng) Dng to mi hay thc hin thay i cho Table tu theo cng dng bao gm : Delete Query, Update Query, Append Query, Make table Quey

II/. Thit k truy vn- Trong Access h tr hai ch thit k truy vn: + Thit k truy vn vi s h tr ca Query Wizard + Thit k truy vn khng c s h tr ca Query Wizard - to truy vn trong ca s Database chn mc Queries ri nhp chut vo nt New, ca s New Query xut hin, ngha cc mc chn nh sau: + Design View: T thit k truy vn + Simple Query Wizard: To truy vn n gin vi s h tr ca cng c Query Wizard + Crosstab Query Wizard: To truy vn tham kho cho vi s h tr ca Query Wizard + Find Duplicates Query Wizard: To truy vn tm nhng mu tin trng lp trn nhng trng no + Find Unmatched Query Wizard: To truy vn tm nhng mu tin m ci trong mt bng hay trong thit k truy vn 1. Thit k truy vn la chn a) Cch to Select query l loi truy vn dng trch - lc - kt xut d liu t nhiu ngun khc nhau t CSDL ra mt bng kt qu. V d: - a ra thng tin chi tit bng lng thng 8; - a ra danh sch cn b l ng vin; - a ra thng tin chi tit v cc ho n bn ra trong ngy hm nay; - a ra doanh thu bn hng ca mt thng no ; 34

- Tt c nhng yu cu dng nh vy (a ra mt danh sch kt qu) u c h s dng SELECT query p ng. Mi yu cu x l d liu cn phi o ra mt Select query p ng; mi query s c mt tn gi (nh cch t tn bng d liu); query sau khi to ra u c th chnh sa li c cu trc cng nh ni dung; qui trnh p ng mi yu cu trn nh sau: To mt query p ng c cc yu cu thi hnh query to thu nhn kt qu. Tip theo minh ho qui trnh cc bc to mt select query p ng yu cu n gin nht: T CSDL Qun l lng cn b, hy a ra bng lng cn b vi nhng thng tin sau: canboID, hoten, ngaysinh, tencv, luongchinh, phucapcv, thuclinh. Trong : luongchinh = Mucluong * Heso Thuclinh = luongchinh + phucapcv Phn tch yu cu: (1). Thng tin yu cu i hi t nhiu bng khc nhau (bng CANBO vi cc ct: canboID, hoten, ngaysinh; bng CHUCVU vi cc ct tencv, phucapcv); (2). C nhng ct thng tin c sn trn CSDL (5 ct k trn) nhng mt s ct yu cu phi c tnh bi biu thc: ct luongchinh v ct thuclinh. Hng dn cch lm: Bc 1: Ra lnh to mt Select query mi bng cch: kch hot th Queries, nhn nt New, chn Design View, nhn Ok (hnh di):

Hoc nhn p chut ln biu tng Create query in Design view trn mn hnh:

35

Bc 2: Chn nhng bng c cha d liu lin quan ln mn hnh thit k query t ca s Show Table (khng thy ca s ny nhn nt Show table trn thanh cng c):

Hy chn cc bng c lin quan (bng CANBO v bng CHUCVU); chn xong nhn Add v nhn Close. Khi mn hnh thit k query xut hin: Bc 3: Khai bo nhng thng tin cn thit cho query:

36

Dng Field: l ni khai bo danh sch cc thng tin (ct d liu) ca bng kt qu. C 2 loi thng tin bi ton yu cu: thng tin c sn t cc trng trn CSDL nh canboID, hoten, tencv, phucapcv v thng tin phi c tnh theo mt biu thc no nh: luongchinh v thuclinh. Mun hin th trng (field) no ln query, ch vic nhn p chut ln tn trng hoc dng chut ko tn chng t cc bng ln dng Field. Hy dng phng php ny a 4 trng canboID, hoten, ngaysinh v phucapcv ln dng Field. Vi 2 ct luongchinh v thuclinh phi a vo query bng cch to mt ct mi vi mt tn gi c tnh bng mt trn dng Field theo c php nh sau:

V d: Luongchinh : Mucluong * Heso to thm ct luongchinh mi Cui cng, mn hnh thit k query nh sau:

37

C th ghi query li vi mt tn gi khi ra lnh ct Alt + S Bc 4: S dng query va to. Mt query sau khi to xong c th: (1) Kch hot chng ly kt qu bng cch: nhn p chut ln tn query. Nu ang trong ch thit k (Design view), nhn nt View trn thanh cng c hoc nhn phi chut ln Query ang thit k chn. Bn s xem c kt qu tr v ca query v c th thao tc bng d liu ny nh trn mt Table (2) Sa li c cu trc thit k query khi chn chng v nhn nt Design. * Mt s thit lp khc cho Query Dng Sort: thit lp th t sp xp d liu trn Query. Mun sp xp d liu cho trng no, thit lp thuc tnh Sort cho trng y. C 2 gi tr cho thuc tnh Sort: Ascending - sp xp tng dn v Descending - sp xp gim dn. Trng no ng trc s c th t sp xp trc.

Dng Show: ch nh hin th hay khng hin th d liu trng ra bng kt qu. Nu chn (checked)- d liu s c hin th ra bng kt qu.

Ch : C 2 li hay mc phi: - Li g sai biu thc: 38

Nguyn nhn gy ra li ny l rt nhiu, c th lit k ra y mt s tnh hung: Tnh hung 1: C th mt trong s tn cc trng bn g trong biu thc c cha du cch hoc cc k t c bit. V d: trng hesoluong ca bn l he so luong th phi g nh sau: [he so luong] thm du mc vung vo 2 u ca tn trng; Tnh hung 2: Sai k php l gc ca biu thc: do vit tha hoc thiu cc ton t, ton hng, hoc cc du m ng ngoc khng khp..; - G khng ng tn trng trong biu thc:

Li ny xy ra khi bn g sai tn trng. Tn hin th trn hp thoi (phucap cv) my tnh khng hiu, c th tn ng ca trng ny l phucapcv. Bn phi ln ti biu thc c cha tn trn v kim tra sa cho ng vi tn trng c trong CSDL. Li ny hay xy ra khi thit k bng t tn cc trng c cha du cch! b) Lc d liu Khc vi bng (Tables), Queries cung cp mt kh nng lc d liu kh hon chnh; C th lc ra nhng d liu theo nhng iu kin phc tp hn, c bit c th chp nhn nhng gi tr lc l cc tham bin. lc d liu, bn phi thit lp iu kin t lc ln vng Criteria ca queries (trong ch ang thit k). Cc iu kin nm trn cng mt dng Criteria s c ni vi nhau bi ton t AND (v); mi dng Criteria s c ni vi nhau bi ton t OR (hoc).

2. TOTAL queries

Tng hp l php x l d liu kh ph bin. Trong Access, query l mt trong nhng cng c x l kh tt vic ny. Total query l mt in hnh. Hy xt mt s yu cu tng hp d liu nh sau:

39

Tt c nhng yu cu trn u c th c p ng bng cc TOTAL query. Di y s hng dn cch to Total query. V d: to query a ra bng tng hp Tenchucvu, Tng s CB (query th 2); Bc 1: To mt select query vi y cc thng tin lin quan bng tng hp:

40

Bc 2: Tu chn Total query bng cch m thc n View | Total hoc nhn nt Total trn thanh cng c; Bc 3: Thit lp cc tu chn Total cho cc trng mt cch ph hp nh sau:

- V bi ton yu cu tng hp thng tin theo tng loi chc v, nn Total ca trng Tenchucvu l Group By; - Trng canboID dng m s cn b tng chc v, nn chn php tng hp l Count. n y to xong query v c th thi hnh thu nhn kt qu. 3. CROSSTAB queries mc 2 chng ta c tm hiu v Total query trong vic p ng cc yu cu tng hp d liu. Trn thc t cn rt nhiu cc yu cu tng hp khc m Total query khng th p ng c. Nhiu trong s nh l:

41

Tt c nhng yu cu dng trn c th s dng CROSSTAB query p ng. Trc khi tm hiu cch to Crosstab query, chng ta hy tm hiu cu trc mt Crosstab, c minh ho bi hnh sau:

- Row heading l tiu cc dng, c cha cc gi tr ca cc trng no lm tiu ch thng k. Mi Crosstab phi c ti thiu 1 trng lm Row heading; - Column heading l tiu cc ct, c cha cc gi tr ca mt trng no lm tiu ch thng k. Mi Crosstab ch c duy nht 01 trng lm Column heading; - Value l vng d liu tng hp (l cc con s). Ch c duy nht mt trng lm Value, tng ng vi n l mt php tng hp hoc: m, tnh tng, tnh trung bnh cng, max, min,.. Cc bc to mt Crosstab query. V d to query a ra c bng tng hp sau:

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Bc 1: To mt select query vi y cc trng c lin quan n php tng hp (khng tha v cng khng th thiu mt trng no) nh sau:

Bc 2: Ra lnh chn kiu Crostab query bng cch m thc n Queries | Crosstab Query; Bc 3: Thit lp cc thuc tnh Total cng nh Crosstab cho cc trng ph hp nh sau:

C th:

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4. MAKE TABLE queries

Select v Total query lun a ra mt bng kt qu- l gi tr tc thi, mi nht c ly ra t CSDL ti thi im . Ti thi im khc khi thi hnh query , rt c th chng ta khng thu li c bng kt qu nh thi im trc . Mun lu li bng kt qu ca mt query ti mt thi im no , trong Access c mt cch l a d liu kt qu query ra mt bng (Table) lu tr lu di bi mt MAKE TABLE query. Cc bc to mt Make table query lu tr kt qu mt query ra mt bng d liu c tin hnh theo 2 bc chnh: Bc 1: To mt Select query hoc mt Total query a ra c bng kt qu cn lu tr; Bc 2: Ra lnh to Make table query t query ang thit k v thi hnh thu c bng kt qu nh mong mun. Gi s to c mt Select query a ra c bng kt qu nh sau:

Bi ton t ra l: a ton b kt qu ca query ang hin th ra mt bng mi c tn bangluong. Cch lm nh sau: Bc 1: m select query to c ch Design View; Bc 2: ra lnh to Make table query bng cch m thc n Queries | Make Table query, hp thoi Make table xut hin: Hy nhp vo tn bng d liu cn lu vo Table Name: Ch : - Nu tn bng nhp vo l mi, Access s t ng to mt bng mi v sao chp ton b d liu m query kt xut c ra bng ny; - Nu tn nhp vo trng mt tn bng c sn, khi thi hnh Access s xo bng c v in vo d liu mi (cn cn nhc khi t tn bng trng tn bng tn ti). Bc 3: thi hnh query nhn kt qu bng cch: - Nu query ang ch thit k, nhn nt Run trn thanh cng c; - Hoc nhy p chut ln query cn thc hin. Khi mt hp thoi cnh bo vic bn ang ra lnh thi hnh mt query c th lm thay i n d liu trn CSDL: 44

Nhn Yes tip tc hoc nhn No hu b lnh. Nu trn CSDL tn ti mt bng c cng tn bng bn ch nh cho query ny lu d liu, Access s hi bn: tn ti bng xxx trn CSDL ri, n s b xo sch khi query ny thi hnh, bn c mun tip tc khng?

Nhn Yes tip tc (tt nhin bng d liu s b xo v thay vo ni dung mi); nhn No hu b. Cui cng mt hp thoi hi mt ln cui xem bn c ng dn xxx bn ghi vo bng ch nh hay khng?

Nhn Yes ng , No hu b. Thi hnh xong hy m bng va to c kim tra kt qu. 5. DELETE queries Delete Query l mt loi Action Query (query hnh ng). N c th gy thay i d liu trong CSDL. Trong trng hp ny, Delete query dng xo cc bn ghi t CSDL tho mn nhng iu kin no . Di y l hng dn to mt Detele query xo i nhng cn b n tui ngh hu ra khi CSDL Qun l lng cn b. Khi query ny thi hnh, danh sch cc cn b n tui hu s b xo khi bng canbo. Cch to query ny nh sau: Bc 1: To mt Select query nh sau:

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Bc 2: i query hin hnh thnh Delete query bng cch m thc n Queries | Delete Query

thi hnh vic xo cn b, nhn c. Khi mt hp thoi cnh bo

nt Run trn thanh cng xut hin:

Nhn Yes ng xo i cc bn ghi (bn ghi xo khng th phc hi li c); nhn No hu b lnh. Phi cn trng trc khi quyt nh lnh xo d liu.

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6. UPDATE queries

Update query dng cp nht d liu mt s trng no trong CSDL. Ging vi Delete query, Update query l loi query hnh ng, lm thay i ni dung d liu trn CSDL. Di y l mt v d s dng Update query tnh gi tr cho ct luongchinh (lng chnh) l mt trng mi c thm vo bng canbo. Bc 1: To mt query v c cha bng canbo v chuyn thnh Update query bng cch m thc n Queries | Update query; hp thoi thit k query nh sau:

Bc 2: Thit lp cc trng cn cp nht d liu bng cch: - Chn tn trng cn cp nht d liu dng Field; - G vo biu thc tnh gi tr cho trng dng Update To; - G vo iu kin tnh ton nu cn dng Criteria. Vi yu cu trn, luongchinh = hesoluong * 290000 ca s thit k query s nh sau:

thi hnh vic xo cn b, nhn c. Khi mt hp thoi cnh bo

nt Run xut hin:

trn thanh cng

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Nhn Yes ng cp nht d liu (d liu sau khi cp nht khng th phc hi li c); nhn No hu b lnh. Phi cn trng trc khi quyt nh lnh ny.

III./ S la chn v biu thc truy vn 1. Ton t LIKETon t LIKE biu din nhng gi tr mang tnh tng i (c th ch ging mt phn gi tr thc). C php biu din ton t ny nh sau: Like Trong c th cha hng v cc k t i din. C 2 k t i din l: - K t * biu din bt k gi tr no; - K t ? biu din mt k t bt k. Mt s v d minh ho ton t LIKE: - Like Nguyn* - lc ra nhng ngi h nguyn. 6 k t u l Nguyn, cc k t cn li l thoi mi; - Like *c* - lc ra nhng ngi c H hoc m hoc Tn l c; - Like */*/1980 - lc ra nhng ngi sinh nm 1980; - Like */11/* - lc ra nhng ngi sinh thng 11; - Like */*/198? - lc ra nhng ngi sinh t nm 1980 n nm 1989; V d : Lc ra nhng cn b c tn l Nam. Ch : Tn ch l mt phn ca trng Hoten:

2. Ton t BETWEEN Ton t BETWEEN lc ra cc gi tr nm trong mt khong no . Thng gii quyt cc yu cu ln hn hoc bng bao nhiu v nh hn hoc bng bao nhiu? C php ton t Between nh sau: Between And V d : Lc ra nhng cn b c 2,000,000>= Thuclinh >=1,000,000

Trong trng hp s dng cc tham bin vo iu kin lc bn lm nh sau: 48

[G mt li nhc trong ngoc vung] ti ng v tr tham s cn thit lp. V d: Lc ra danh sch cc cn b phng ban no , lm nh sau:

Khi thi hnh query, mt hp thoi yu cu g vo tham s cn lc:

3. Cc hm dng tng hp d liu Count m; Sum - tnh tng; AVG - tnh trung bnh cng; Max - xc nh gi tr ln nht; Min - xc nh gi tr nh nht;

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Bi tp 1. Thc hin trn CSDL Qun l lng cn b cc yu cu: Bi s 1: Hy tnh v in ra bng lng ca c quan bao gm cc thng tin: Hoten, ngaysinh, tenchucvu, tenphongban, luongchinh, phucapcv, dangphi, congdoanphi, thuclinh. Trong : Luongchinh = hesoluong * 290000 Dangphi = 20,000 vi nhng ai l ng vin Congdoanphi = 5%Luongchinh vi nhng ai vo cng on Bi s 2: Hy a ra danh sch cc cn b l ng vin m cha vo cng on; Bi s 3: Hy lc ra danh sch cn b ca mt phng ban no , tn phng ban c nhp t bn phm khi query c kch hot; Bi s 4: Hy lc ra danh sch cn b l ng vin v c thc lnh ln hn mt s no - c nhp t bn phm khi query c kch hot; Bi s 5: Hy lc ra danh sch cn b m nm sinh ri vo trong mt khong nm no c nhp vo t bn phm. V d: khi kch hot query, Access yu cu nhp vo khong nm sinh t nm no, n nm no. Khi query s lc ra danh sch cc cn b tho mn iu kin ; Bi s 6: Lc ra danh sch cn b c tn c nhp vo t bn phm khi kch hot query. V d: khi query kch hot s hi: G vo tn cn xem? Sau khi g vo mt tn (c th c h hoc c h v tn), my tnh s lc ra danh sch cn b tho mn iu kin; Bi s 7: Lc ra danh sch cn b n tui ngh hu, bit rng iu kin ngh hu xc nh nh sau: - L Nam gii, tui >=60 - L N gii, tui >=55 Bi s 8: Hy a ra bng tng hp s cn b vo ng hay cha vo ng theo gii tnh nh sau:

s

Bi

9: Hy a ra bng tng hp tng s cn b theo tng loi chc v ca cc phng ban nh sau:50

Bi s 10: a ra bng tng hp v chc v theo gii tnh nh sau:

2. Thc hin trn CSDL Qun l bn hng cc yu cu: Bi s 11: To query hin th chi tit thng tin tng hng bn:

Bi s 12: To query a ra bng tng hp tng tin bn c tng ngy ca ca hng nh sau:

Bi s 13: To bng tnh tng tin tng ho n bn hng nh sau:

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Bi 4: XY DNG FORMI./ Khi nim FormsKhi s dng mt ng dng, a phn cng vic ca ngi dng lm trn cc hp thoi (Dialogue), ca s (Windows). C 2 thnh phn ny trong lp trnh u c gi l Form. Vi ngi dng, Form l giao din s dng phn mm; cn vi nhng ngi pht trin phn mm, Form l nhng ci m h phi ngh, phi thit k v to ra sao cho ngi dng h cm thy rt thoi mi, ph hp v d dng. C 2 mi trng dng to Form trong Access: - S dng trnh Form Wizard. y l cch rt n gin, nhanh chng, d dng gip to nhanh mt Form. Tuy nhin Form c to ra c nhiu hn ch, khng gn gi vi yu cu ca ngi dng; - S dng trnh Form Design View - mt cng c tng i hon chnh to ra cc form p ng nhiu yu cu khc nhau ca ngi s dng.

II./ S dng FORM WIZARDForm wizard l cng c trn Access gip ngi dng nhanh chng v d dng to ra mt Form dng lm giao din nhp d liu cho cc bng trn CSDL. Di y trnh by cc bc to mt form lm giao din nhp d liu cho bng CANBO trong CSDL Qun l lng cn b. (bn phi chc chn to hon chnh cu trc CSDL trn): Bc 1: Kch hot trnh Form Wizard th Forms, nhn nt New, chn Form Wizard, nhn OK;

Hoc c th nhn p chut ln Shortcut Creat Form by using Form wizard Bc 2: Chn cc thng tin cn a ln form. y l bc quan trng nht khai bo nhng trng d liu no ca form s c th c nhp d liu thng qua form ang to. Hc vin phi cc k cn nhc cc thng tin y: chn bng no v chn nhng trng no cho ng?

52

- Chn bng - ni c trng cn a ln form nhp d liu hp Tables/Queries; - Tip theo a cc trng cn nhp d liu ln form t danh sch Available Fields: sang danh sch Selected Fields: bng cc nt lnh: >, >>, ,