1 BI GING PHN TCH THIT K H THNG THNG TINTRNG I HC K THUT CNG NGH
TP.HCM KHOA CNG NGH THNG TIN Bin son: ThS. Vn Nh Bch B, ThS. V Hong
Khang. B mn: H thng Thng tin, Khoa CNTT, trng H K thut Cng ngh
TP.HCM 2 Chng 1 TNG QUAN PHN TCH THIT K MT HTTT KHI NIM C BN:
1.1.KN Phn tch. Cc phng php Ngin cu khoa hc tm hiu nhn bit mt
HTTT:1.1.1. PP so snh tng t - tng phn. 1.1.2. PP Th v bit. 1.1.3.
PP Logic. 1.1.4. PP Qui np. 1.1.5. PP Loi suy. 1.1.6. PP Xc xut
thng k. 1.1.7. PP Phn tch & tng hp. v.vv 1.2.KN HTTT. 1.2.1.
HTTT? 1.2.2. M hnh phn cp HTTT. 1.2.3. Ba trc biu din ca mt HTTT.
1.3.Cc mt phng tng quan gia 3 trc. 1.3.1. Mt phng mc nhn thc - Cc
thnh phn. 1.3.2. Mt phng mc nhn thc - Cc bc pht trin. 1.3.3. Mt
phng Cc thnh phn - Cc bc pht trin 3 1.1.1. PP so snh tng t -Tng
phn. Lp trnh theo mu. Vn mu. Cc dng ca bi ton. Trinkhaiccmhnhkinht
mu. Mu biu. Bt chc. Sosnhvtngphn(Cccp i ngu, thuyt m dng)
uim:Ktqunhanh,dtrin khai Khuyt im: Ktqukimtragimtheothi gian (v m
hnh d nhn rng). Trit tiu tnh sng to. Thi quen khng tt. Phn lp cc i
tng d dng, d khi qut v tng qut t cc mu ph bin Vd 1: Vd 2: Vd 3: Vd
4: Vd 5: Vd 6: u im? Khuyt im? Vd 7. Vd 8. Vd 9. Vd10. 4 1.1.2. PP
Th v bit. Cccngvictiphng th nghim. Tm kim v thm d. Thm him. Giao
din trc quan. (Whatyouseeiswhatyou get). u: Kt qu c th nhanhnu mu
nh.Dthchin.Ktquc th bt ng ln. Khuyt:Khnggianmu lnqutrnhthcth
bngnthp.Ktqu KTbphsnnukinh phthlnvkhng thnh cng. Vd 1. Vd 2. Vd 3.
Vd 4. u? Khuyt ? 5 1.1.3. PP Logic. p => q Logic c in, Logic m.
H tin , Lut dn. nh l, H qu. Pht biu bi ton. Phn chng (!q => !p).
u:Phngphpluncht ch v c HT v c chiu su. Khuyt:PhictnhlintcminmvngHT
(p1=>p2=>pn).Tinhnglogic m c tnh tng i. Kinthcphttrinchiusu,
hnchchiurngvtng quan. Vd 1. Vd 2. Vd 3. Vd 4. Vd 5. Vd 6. u? Khuyt?
Nhn ti khng i tui (pht trin tn cng ca chiu su). Lnh o gii phi c thi
gian (Ci nhn bao qut v kinh nghim sng) 6 1.1.4. PP Qui np.
(N=n0)=true; G/s: (N=k)=true,k >=n0; CM: (N=k +1)=true. KL:
(N=n)=true, n >=n0; Tm kim qui lut. Kinhnghimckhi qut.
uim:Ktqupt qui lut d nhn bit. o c d truyn t. Khuyt:Ktqucaqui np t
gp, l tng qu! Vd 1. Vd 2. Vd 3. Vd 4. Vd 5. Vd 6. u? Khuyt? 7
1.1.5. PP Loi suy. X={x/ p1(x)&p2(x)..pn(x)=true}.
-pj(y)=False, j=1..n KL:ye X. La thc. Chng c ngoi phm. Cm on v cho
php u:Nhnbitcsng t vic loi b s t. i t tnh cht bit c bn cht.
Khuytim:Phthucvo khnggianmuvstnh cht nhn bit c chnh xc? Vd 1 Vd 2
Vd 3 u? Khuyt? 8 1.1.6 PP Xc xut thng k. Tnh hung: Kh nng cao nht.
Trng hp t khi xy ra. Thng thng, t khi. Trong mt bt hnh dong.
Triuchng,chnon, d bo v..v.. u:Phthuykinhnghim tchly.Tnhthcnghim
cao. Khuyt:chnhxcc tnhchttngi.Kt qu ph thuc vo vic ly mu. Vd 1. Vd
2. Vd 3. Vd 4. Vd 5 u? Khuyt? 9 1.1.7. PP phn tch & tng hp. Phn
tch: Chia nh nhn c bn cht v thnh phn cu thnh. Tng hp: Phi hp, lin h
c ci nhn ang kt v ph thuc. Lnhvc:Chuyngia,tvn,bnh
lunvin,phntchvin,nhlnh o. Nhkhoahcitncngcachiu sucnchuynmn,thngthi
lnhhiskin,svt,ihiphi cti(chiusu).Nhnhnvni theo chiu rng ca con ngi
v lch scnihithigianvchim nghimcucsngangkt phc tp ca con ngi v cuc
sng cnphicc(rnglng,bao la). Nh lnh o t nc phi c ti
(cchiusu)vc(chiurng)v vy phi gii v phn tch v tng hp.
u:Nhnthccbncht,ni dungcasvtmtcchy nht.Nhnthcvatheochiusu
(phntch)vatheobrng(tng hp). Khuyt:Cnnhiuthigian,cnkinh
nghim,tringhimvkinthcnht nh nhn bit vn mt cch u . Vd 1 Vd 2 Vd 3 Vd
4 u? Khuyt? 10 1.2.1-HTTT? Khi nim HTTT: -DL: Thng tin nguyn t,
thng tin c bn. -Tnh cht DL: * Trc quan-tru tng * Gi tr theo thi
gian v khng gian. -HTTT: Tp hp DL c sp xp theo mc ch nht nh. Ton b
kin thc ca loi ngi c ghi nhn mt cch c HT t qu kh, hin ti v d bo c
tng lai trong mi lnh vc ca cuc sng vt cht, tinh thn, k c tm linh,
hin hu v gi nh. Nguyn t: Khng th b nh, chia ct ? VD? Trc quan: Thy
v nhn bit ngay? Tru tng: c din t v nhn bit nhiu gi tr trc quan? Cho
Vd: DL tru tng? S HD: 005. Trc quan hay tru tng? 50oC? Gi tr theo
thi gian v khng gian? L gi tr gn lin vi i tng tn ti vithi gian nht
nh trong mi trng khng gian ng cnh nht nh?VD? Kin thc ton hc c phi l
HTTT? 11 1.2.2-M hnh phn cp HTTT. Nhn xt: -Cao-Thp? -Nhiu-t ?
-Nghip v? -Khi lng kin thc-Thi gian o to -Khi lng cng vic? -S lng
nhn s lm vic cho tng HT. -Vai tr, lng bng khc nhau cho tng HT. -Gi
tr TT ca tng HT? -Phn b chi ph cho tng n v ca HT. Vn dng m hnh phn
cp, hy m t cng vic v thng tin ti cc c quan x nghip: -Siu th. -Cng
ty DL. -Trng hc. Cch tip cn tm hiu ca tng HT? HTTT RA QUYT NHHTTT X
LHTTTTC V12 1.2.3-Ba trc biu din ca mt HTTT. i/Cc thnh phn ca HTTT:
*D liu. *X l. *B x l. *Truyn thng. *Con ngi. ii/Cc mc nhn thc HTTT:
*Nhn thc mc quan nim. *Nhn thc mc logic. *Nhn thc mc vtl. iii/Cc bc
pht trin HTTT: *Phn tch. *Thit k. *Ci t. Cc mc nhn thc HTTTCc thnh
phn ca HTTT Cc bc pht trin HTTT13 1.3.1.Mt phng mc nhn thc - Cc
thnh phn. DLX LyNgiBo x lyT. thong QNMo hnh QNDL: Xac nh noi dung d
lieu ma HTTT phai quan ly Mo hnh QNXL the hien kha canh Them sa xoa
d lieu Ngi s dung tng lai Ngi to chc e an khong cankhong can TCAi
chu trach nhiem phan nao? Bo tr v tr nhap xuat d lieu. MH DL quan
he Mo hnh TCXL Phan tch vien Ky thuat vien: nhap lieu va chuyen
vien phan cng Bo nh ia cng T.b ngoai vi theo chuan loai? Chuan loai
mang (Qui mo, tnh nang) VL He thng tap tin XD thanh phan t lieu
thanh CSDL Giao dien Cac chng trnh Ke hoach thc hien Phan tch, lap
trinh vien va Ky thuat vien May nao cau hnh nao? Phan mem nao?
Chuan Nghi thc truyen va mang cu the Mc nhn thc quan nim thnh phn
no l quan trng? Mc t chc thnh phn no l quan trng? Mc nhn thc vt l
thnh phn no l quan trng? Vai tr con ngi no l cn thit nht. 14 1.3.2.
Mt phng mc nhn thc - Cc bc pht trin. Phan TchThiet KeCai at Quan
Niem To Chc Vat Ly Mc quan trng ca cc mc nhn i vi cc bc pht trin?
Vai tr nhn thc mc quan nim i vi mc thit k? Vai tr nhn thc t chc i
vi mc ci t? Nu thut ton, thut gii c phi l mc t chc ca bc pht trin
ci t? 15 1.3.3.Mt phng Cc thnh phn- Cc bc pht trin. DLX LyNgiBo x
lyT. thong PT PT vien, NSD Khong can TK PT vien, LT vien HT con,
phan cong C LT vien, NSD CT con, cac Modun Cc thnh phn ca HTTT c
pht trin u theo cc bc pht trin ca Phn tch-Thit k-Ci t. D liu trong
bc ci t c khc g vi d liu ca bc thit k v bc phn tch? 16 CHNG 2: PHN
TCH MT NHU CU NG DNG TIN HC 2.1Khostthctvphntchhin trng.
2.1.1Xcnhmcchngdngtin hc. 2.1.2Phng php thc hin.
2.2.Ccbcthchintrongqutrnh phn tch. 2.3.Nuccquytcqunl(RBTV)v tm nh
hng. 2.4.Phntchccyucuxlvkt xut. 2.4.1. Phn tch ni dung kt xut.
2.4.2. Phc tho s logic d liu. 2.4.3.Phntchccdliubin ng.
2.4.4.Phntchccdliuthng trc. 2.4.5. Tng hp d liu. 2.4.6. Phn tch cc
x l. Vd:Mphngmthin trngHTTTtrongmt doanh nghip? Xc nh mc ch tin hc
ha ca HTTT . Dngccphngphp no?Vndngkthut g? tm hiu HTTT .
BitpTH:Lphs phntchchovickho st v tm hiu mt HTTT. tithchintng
nhmcphncngcng viccthchotng thnhvinvlpk hoch tm hiu.17 2.1 Kho st
thc t v phn tch hin trng.2.1.1 Xc nh mc ch ng dng tin hc. nm c chi
tit ca lnh vc cn tin hc ha chng ta cn tm hiu hin trng ca lnh vc ,
bao gm: *Mc tiu chnh ca n: Xcnh cho c gii hn ca phn tch. *Tin hnh
thu thp:+Danh sch cc v tr lm vic +Cc tc v, kt xut cn thc hin +Cc
thng tin cn x l +Chu k, thi gian thc hin +Cc quy tc cn p dng thc
hin cng vic.. *c t kt qu thu thp Gii hn ca phn tch c phi l gii hn
ca lnh vc cn tm hiu? ng dng tin hc ha hin ti ca HT c phi hin trng
ca lnh vc i vi vn ng dng tin hc? Trong qu trnh tin hnh thu thp ta
cn phn tch u v khuyt im ca HT hin ti? u v khuyt gip ch g trong qu
trnh tm hiu v xy dng HTTT qun l v ng dng tin hc. Nu cc v d? 18 2.1
Kho st thc t v phn tch hin trng. 2.1.2 Phng php thc hin. Trong nhiu
phng php nghin cu v tm hiu ng dng tin hc ch yu l dng phng php phn
tch tng hp vi cc k thut sau: Phng vn Bng cu hi Nghin cu ti liu vn
bn Quan st thc t Tmhiuyutthnhcng trng im S dng nhm phn tch. Nu u v
khuyt im ca cc k thut trong qu trnh phn tch tm hiung dng tin hc ha
mt HTTT? Cc bc chun b ca tng k thut? Mi nhm chn mtk thut trnh by
vic tm hiu ng dng Tin Hc ha mt HTTT c th 19 2.4.1. Phn tch ni dung
kt xut. Kt qu ca kt xut c th l: *Mt bo biu (report): Kt xut c tnh
cht tng hp (nhiu output kt hp nhiuinput). *Di dng mt cng thc, hay
mt la chn: Tm hiu ni dung ca quy tc (output). *Di dng ph thuc: Tnh
duy nht ca d liu nhp da vo d liu ang c (Kt xut duyn phn, Input duy
nhtda vo mt input). Vd1? Vd2? Vd3? Nhp ID cha khi bit ID con. Input
mt ln, kt xut khp mi ni? Thng tin ca khch hng c mt trong mi ha n m
khng cn nhp. 20 2.4.2. Phc tho s logic d liu. Phc tho lc quan h nhn
dng t cc mu biu. Lit k cc thuc tnh t cc lc quan h v xc nh thuc tnh
c lp, thuc tnh ph thuc (Cng thc, la chn hay ph thuc hm?). Dliu theo
tng chc nng hay theo m hnh t chc. Vd 1? Vd 2? Vd 3?21 2.4.3.Phn tch
cc d liu bin ng. Dliubinngldliu cthayitrongkhong thi gian nht nh.
Chailoidliubinng: Binngtcthi,binng theo thi gian c tr.
*Binngtcthilmt trngthicaDLccp nhttcthikhicmttc ng thay i.
Vd:TrnhtrngxeTaxi(u, Ch khch, Rc khch?). *DLbinngtheothigian
ctrlDLccpnht sau mt qui nh ca mc thi gian nht nh. Vd:DLbocodoanhthu
trong ngy, Tn kho. Vd 1? Vd 2? DL bin ng tc thi? Vd 3? DL bin ng
theo thi gian c tr. Thng thng loi d liu no c lu tr theo vt ca thi
gian? Biu nhp tim trn mn hnh thuc loi d liu no? 22 2.4.4. Phn tch
cc d liu thng trc. DLthngtrcldliu c tnh n nh cao. t c bin ng.
Tngtrng(slng) chm theo thi gian. Nguntinguynlinquan ti nghip v ca
HT. Skin,Svt,Cci tnglconngihayt chc c trong HTTT Vd1? Vd2? Vd3?
Vd4? Vd5? Khi xy dng xong PM ngi ta thng nhp liu cho DL thng trc? L
do? 23 2.4.5. Tng hp d liu. Cc bc tng hp DL: -b1.Thuthpcchs phn
tch. -b2. Loi b DL d tha v trng lp. -b3. Phn loi DL. Sp xp cc s .
-b4. Xy dng MH QN DL. -b5. MH logic DL. -b6. B t in DL.
-b7.Spxpvnuthut ton cho cc RB DL Mi Nhm trnh by b1, b2, b3kt qu ca
qu trnh phn tch, tm hiu mt HTTT ca nhm chn. 24 2.4.6. Phn tch cc x
l. X l theo l hay x l n. X l tc thi hay thi gian c tr. X l th cng,
t ng, bn t ng. X l n gin hay phc tp (nghip v, thut ton). X l trnh t
hay ng b. X l theo thng dch hay bin dch. Thi ca x l khi x l c s c.
Thi gian, khng gian v tn xut x l (Tc , ni nhn, s ln) Vd2? Vd3? Vd4?
Vd5? Vd6? Vd7? Vd8? 25 CHNG 3: PHN TCH V THIT K THNH PHN D LIU CA
MT H THNG HTTT-THIT K M HNH D LIU QUAN NIM. 3.1 M hnh thc th kt hp.
Mhnhthcth-kthpchnhl mhnhquannimdliuhaycn gilmhnhnhnthcdliu
mcquannim.MtMhnhttphi tha mn cc yu t: -i/Lmrccloiitngcnquan tm.
-ii/Thycmiquanhcbn gia cc loi i tng -iii/NucmtsRBcbnca cc loi i
tng. 3.2 Cc khi nim c s. *3.2.1 Thc th *3.2.2Loi thc th. *3.2.3Loi
mi kt hp. *3.2.4Bnscaloithcththam gia vo MKH. *3.2.5 Kha ca Loi
MKH. DLquannimcphilsquanh giatrcccthnhphnHTTTvi cc mc nhn thc HTTT?
v qua cc bcphttrinntrthnhthitk m hnh DL quan nim?
Vicxydngmhnhnychnhl thit k m hnh d liu quan nim? Hylitkccmhnhmbn
bit?Hynunghacaccm hnh.Mhnhmbocc yutnonhnbitmtmhnh tt? Cc khi nim
lin quanti thc th: *i tng, lp? V d? *Quan h, loi quan h, l quan h?
V d? 26 CHNG 3: PHN TCH V THIT K THNH PHN D LIU CA MT H THNG
HTTT-THIT K M HNH D LIU QUAN NIM. 3.3 Ccnguyn tckhixy dng m hnh thc
th - kt hp. 3.4 Cc bc thc hin khixy dng m hnh thc th - kt hp.
3.5MHnhThcthkthpm rng. *3.5.1 Loi mi kt hp qui. *3.5.2Loimikthpnh
ngha trn mt loi MKH khc. *3.5.3 Bn s ca mtloi MKH.
*3.5.4Chuynbithavtng qut ha.*3.5.5Giahailoithcthc nhiu loi MKH, Mi
loi MKH c mt ng ngha duy nht. Ti sao ta gi 1 a ch c th: 54 Hong
Diu, P.3, Q.3, TP.HCM l mt quan h C? Mt i tng trong th gii thc khi
lu tr trong HTTT c lm r bicc gi tr (DL) ca mt quan h c th? V d 1 i
tng: Chic xe ny ca Cty MaiLinhc lu tr nh th no? n l mt quan h? 27
3.2.1 Thc th Thcthlmtitngtnti trong th gii thc c lm r bi
ccgitrvctnhclpcao. Nghalstntithcthny khng ph thuc vo thc th khc.
Vd:1thcthhan:006, 28/07/2010 nTpcsdl: KN lin quan ti thc
th*Quanh:lmtitngtnti trong th gii thc c lm r (m
t)biccgitrclinquanvi nhau. Vd:1quanhhan:006, 28/07/2010, kh0076.
*Loiquanh:Ttcccquanh ccngtnhchtmt.Tnhcht mtgilthuctnhcaloi
quanh.Loiquanhcbiu din di dng L quan h. Vd:Loiquanhhanlttc
cchancbiudindi dngLquanh:HoaDon(SoHD, NgayLap, Mkh) Gi s ta c 1 thc
th:05DTH01,Lp05HCNTT01hygiithch2trng hp sau: i/Ti sao 1 quan h SV:
004,TrnVnA,Nam,06/06/1990,05DTH01khngl thc th? ii/Ti sao 1 quan h
SV: 004, Trn Vn A, Nam, 06/06/1990l thc th?
Thcthlquanh?Quanhlthcth?Thcthv quan h u l i tng? Cu hi n tp CSDL:
i/Thuc tnh quan h? ii/Kha ca quan h? Kha ca L quan h? iii/006 l kha
ca 1 quan h Ha n? SoHD l kha ca lquanhHoaDon?Haylthuctnhkhacalquan
hHoaDon. iv/N r rng kha ca quan hv kha ca L quan h? S mng c phi l
kha ca L quan h ConNguoi? vui: Ai l ngi u tin pht hin kha? Gii
thch? Mi SV chn 1 Vd v kha? Xc nh kha ca cc L quan h sau:
-TKB(mp,thu,gbd,sotiet,mgv,mlop,mmh) -GiayKethon(sqd, ngayKh,
cmndvo,cmndc, lanv, lanc)-Lamban(mct,mtr,phut). Kha c phi do PTV ch
nh? Cl quan h no khng c kha? Gp nh danh M l ta chn kha? 28 3.2.2Loi
thc th. KN:Loithcthlttcccthcthc cng tnh cht m t. Tnh cht m t gi l
thuc tnh ca loi thc th. Mi loi thc th c biu din di dng: V d:
Khacathcth:Ltpgitrbnhtdngphnbitgiaccthcthtrong cng mt loi.
Khacaloithcth:Tpthuctnhb nhtmgitrcandngphnbit
thcthnyvithcthkhctrongcng mt loi. Vd1? Vd2? -tt1 -tt2 - .. -ttn
HoaDon -Sohd -NgLap 29 3.2.2Loi thc th C 3 loi Loi thc th:*Loi thc
th c bn (trc quan): Hng ha, s vt, ngun ti nguyn ca HT c tnh n nh
cao, thng khng c thuc tnh thi gian (nu c t quan trng). V d:
Mathang, Kho, BaiHat, PhongHoc, v.v *Loi thc th i Tng Ngoi (d nhn
bit): Con ngi hay t chc. *Loi thc th nghip v (tru tng): Lun c thuc
tnh thi gian, s lng thc th trong loi thc th tng trng theo thi gian
rt nhanh. V d: HopDong, HoaDon, PhieuXuat, PhieuNhap, vv 005 l kha
ca thc th 1 ha n, Sohd l kha ca loi thc th HoaDon? Ngi ta hay lm
dng t: Sohd l kha ca thc th HoaDon? Phn bit kha v thuc tnh kha? 30
3.2.3Loi mi kt hp. Mi kt hp: Gia2thcthcquanhngnghavinhauto
thnhmikthp.Gitrcamikthptnhtl cc gi tr kha ca thc th tham gia v c th
c gi tr ring ca mi kt hp. Loi Mi kt hp: Gia2
LoithcthAvBcccthcthquan h ng ngha vi nhau to thnh loi mi kt hp AB
(c thttnkhc).Thuctnhcaloimikthpt nht l cc thuc tnh kha ca cc loi
thc th tham giangoiracncthuctnhringcaloimikt hp. Tnh Cht ca MKH:
*Mimikthpchmangmtngnghaduynht. Gia 2thcthc nhiuquan h ng nghaphic
nhiu MKH. *Vimtngngha(mtMKH)mtthcthcth khng quan h vi bt k thc th
no, hoc quan h mt hoc quan h nhiu thc th khc. 1 Thc th nhn vin Mi
kt hp? Ng ngha ? 1 Thc th phng ban Loi Mi kt Hp? Ng ngha? Kha ca
Loi MKH? 005TrnVnA06/10/1970Nam 01Ti v 005, 01, G NhanVien PhongBan
Thuoc -MSNV -MPB -CV MSNVHoTenNgSinhPhai 005Trn VnA06/10/1970Nam
006Ng Th B10/01/1980N 007Cao Tun01/12/1976Nam MPBTenPB 01TiV 02T
Chc MSNV- HoTen- Ngsinh- Phai- MPB- TenPB- 31 3.2.4 Bn s ca loi thc
th tham gia vo MKH. Bn s ca loi thc th tham gia vo MKH l: *(Min,
Max), Min, Max e N. *Min: S th hin ti thiu ca thc th tham gia vo
MKH. *Max: S th hin ti a ca thc th tham gia vo MKH. Nhn xt: *Min0,
v nu min=0 th max=0. Vy hai loi thc th khng c quan h ng ngha.
*Min>1 th Max>1. Qui c: *Min>1 ta ghi Min=1 *Max>1 ta
ghi Max=n. Vd1: Vd 2: Vd3: 32 3.2.4 Bn s ca loi thc th tham gia vo
MKH. Kh nng cp bn s: (0,1), (1,1), (0,n), (1,n) - Hai cp bn s gia
hai loi thc th: *(0,1)-(0,1): Quan h mt-mt.
*(0,1)-(0,n):Quanhmt-nhiu,quanhcon-cha.Chacthkhngcconhocnhiucon v
conhoc khng bit cha hoc c mt cha duy nht.
*(0,1)-(1,n):Quanhmt-nhiu,quanhcon-cha.Chacnhiuconvconhockhngbit
cha hoc c mt cha duy nht. *(1,1)-(0,1):Quanhmt-mt,Mtsthcth bn phi
khng tham gia MKH. *(1,1)-(1,1):Quanhmt-mt.Hailoithcth cth gom li
mt loi, v loi thc th gom c 2 kha.
*(1,1)-(0,n):Quanhmtnhiu,quanhcon-cha, cha c th khng c con v con
phi c mt cha duy nht. *(1,1)-(1,n):Quanhmtnhiu,quanhcon-cha, mi cha
u c con v con phi c mt cha duy nht. *(1,n)-(0,n)
*(1,n)-(1,n)Nhiu_Nhiu*(0,n)-(0,n) Qui c: MatHang
MaHgTenHgQuiCachnGi? AKemPS1Hp20.000? BngT BhKg15.000? CGo
NtKg25.000? HoaDon SoHdNgayLap 0101/08/2010 0201/08/2010
0302/08/2010 CTHoaDon SoHdMaHgSLnGi? 01A3? 02A5? 02B10? 03A6?
HoaDon SoHD- NgayLap- MatHang CTHoaDon -MaHg -TenHg -QuiCach
-onGia? -SL -DonGia (1,2)(0,3) (1,n)(0,n) 33 3.2.5 Kha ca loi MKH.
KhacaloiMKHcsuyratkhaca thc th tham gia vo mi kt hp, da vo cp bn s
ca thc th tham gia vo MKH. ThuctnhringcaMKHkhngthamgiavo
khacaMKHvphthucyvokha ca MKH. Khi ci t, sau khi chuyn cc loi thc th
v ccloiMKHsangloiquanh,ngitagom cc loi quan h cng kha thnh mt loi
quan h. Trnghp2,3,6,7:KhacaloithcthA trng vi kha ca loi MKH. Ngi ta
gom loi thc th A v loi MKH thnh 1 loi quan h. Trng hp 1, 4, 5: C 2
kha. C 2 cch gom? Chn cch gom? L do? Sinh vin hy trnh by cc VD sau:
VD 1? Trng 1? VD 2? Trng 2? VD 10? Trng 10? Loi MKH gia 2 loi thc
th l MKH 2 ngi. Loi MKH gia 3 loi thc th l MKH 3 ngi. Xc nh kha
caloi MKH 3 ngi? Vd cho 3 ngi? Trng hpCp Bn sthc th A Cp Bn sThc th
B Khacaloi MKH 1(0,1)(0,1)2 Kha: Kha1 l kha loi thc th A, Kha 2 l
kha loi thc th B 2(0,1)(0,n)1 Kha: l kha loi thc th A 3(0,1)(1,n)1
Kha: l kha loi thc th A 4(1,1)(0,1)2 Kha: Kha1 l kha loi thc th A,
Kha 2 l kha loi thc th B 5(1,1)(1,1)2 Kha: Kha1 l kha loi thc th A,
Kha 2 l kha loi thc th B 6(1,1)(0,n)1 Kha: l kha loi thc th A
7(1,1)(1,n)1 Kha: l kha loi thc th A 8(1,n)(0,n)1 Kha: L cc thuc
tnh kha ca loi thc th A v kha ca loi thc thB . 9(1,n)(1,n)1 Kha: L
cc thuc tnh kha ca loi thc th A v kha ca loi thc th B .
10(0,n)(0,n)1 Kha: L cc thuc tnh kha ca loi thc th A v kha ca loi
thc th B . Xem thm 34 3.3 Cc nguyn tc khi xy dng m hnh thc th kt
hp. Mi loi thc th khi xy dng phi m bo:i/ Phi c gi tr lu tr v khai
thc ii/ Phi c t hai thc th tr ln (hai th hin). iii/ Tn ca loi thc
th phi l danh t. iv/Mtloithcthclmr(nhnbit)bi cc yu t: *Tn gi. *Thuc
tnh. *Mtvithhincth(viitng,vidng gi tr c th)
v/Ccthuctnhtrongmtloithcthkhng c ph thuc ln nhau ngoi tr ph thuc y
vo kha.vi/ Mi loi thc th phi m bo tnh c lp.
vii/Miloithcththucmttrongccdanh mc sau:
*Danhmcthngtincbn:Tnhnnhcao, khng c thuc tnh thi gian, nu ln s kin,
s vt c bn, ngun ti nguyn ca HT. *Danhmcitngngoi:Conngihayt chc.
*Danh mc cc nghip v: Lun c thuc tnh thi gian, danh mc cc i tng tru
tng Cu hi: Hy nu cc v d cc loi thc th b vi phm cc nguyn tc (i
),(ii), (iii), (iv) lm r cch xy dng m hnh hn? V sao phi tha nguyn
tc (v),(vi) cho v d? Hy nu 2 danh mc cc nghip v qun l cp bng ? Vd1?
Nguyn tc I, Thc th Vd2? Nguyn tc II, Thc th Vd3? Nguyn tc III, Thc
th Vd4? Nguyn tc IV, Thc th Vd5? Nguyn tc V, Thc th Vd6? Nguyn tc
VI, Thc th Vd7? Nguyn tc VII, Thc th-Dm TT c bn Vd8? Nguyn tc VII,
Thc th-Dm TTi tng ngoi. Vd9? Nguyn tc VII, Thc th-Dm TTcc nghip v
35 3.3 Cc nguyn tc khi xy dng m hnh thc th kt hp.
Mimikthpkhixydngphim bo:i/Gia ccloithcthphicquan h ng ngha cn thit
cho qun l. ii/Mi kt hp to ra phi c gi tr lu tr v khai thc.
iii/Giahailoithcthcthcnhiu mikthp.Mimikthpchmang mt ng ngha duy
nht. iv/Khacamikthpcsuyrat khacaccloithcththamgiavo
mikthp,davobnscathc th tham gia vo mi kt hp. v/Thuc tnh ca mi kt hp
t nht bao gmthuctnhkhacathcththam giavomikthp,ngoiracnc
thuctnhringcamikthp,thuc tnhnykhngthamgiavokhaca mi kt hp. Vd10?
Nguyn tc i, MKH
Vd11? Nguyn tc ii, MKH. Vd12? Nguyn tc iii, MKH Vd13? Nguyn tc
iv, MKH Vd14? Nguyn tc v, MKH 36 3.4 Cc bc thc hin khixy dng m hnh
thc th kt hp. (i) Nhn dng loi thc th c bn:*S kin, s vt, ngun ti
nguyn ca HT *Tnh n nhcao, t cp nht, khng c thuc tnh thi gian *Khi
xy dng xong phn mm, khch hng thng yu cu Cty nhp liu phn thng tin
ny. V d: Mathang, Benh, Thuoc,Loi hng, MucLuong,Khuvuc,
MonHoc.v.v... (ii) Nhn dng loi thc th i tng ngoi: *Con ngi hay t
chc. *Khch hng, nh cung cp, nhn s trong cng vic, cc t chc lin quan.
V d: Khoa, PhongBan, To, Nhom, Tinh_Tp, KhuVuc.v.v Vd1? Vd2? 37 3.4
Cc bc thc hin khixy dng m hnh thc th kt hp. (iii) Nhn dng loi thc
th nghip v: *Loi thc th lin quan cc i tng tru tng, c lin quan ti
cng vic, din ra hng ngy, hng gi. *Thng c thuc tnh thi gian.
*Ccthngklinquantiktqu hotthngtheokhongthigian ca loi thc th ny. *V
d: HoaDon, DonDatHang, PhieuKhambenh, ToaThuoc, v..v (iv) Kim tra
tnh hp l ca loi thc th: *Danh t. *C tnh lu tr v khai thc. *C 2 th
hin (2 dng d liu) tr ln. *Ccthuctnhkhngphthucln nhau, ngoi tr kha.
Vd3? Vd4. 38 3.4 Cc bc thc hin khi xy dng m hnh thc th kt hp. (v)
Xc nh cc mi kt hp bc 1: *Xcnh ng ngha gia cc loi thc th? *Xcnh cp
bn s ca loi thc th tham gia vo loi MKH. *MKH phi c gi tr lu tr v
khai thc. *Lpt hp cc MKH c th: +Loi thc th (i)-(i), (ii)-(ii),
(iii)-(iii): Thng l MKH phn cp theoCha-Con hocbnh ng Mt-Mt. +Loi
thc th (i)-(ii): Thng l MKH trc thuc, s hu,Cha-Con. +Loi thc th
(i)-(iii): Thng l chi tit ca nghip v, Mkh Nhiu-Nhiu + Loi thc th
(ii)-(iii):Thng l MKH s hu nghip v, MKh Cha-con. (vi) Xc nh mi kt
hp bc 2 (mc sau). *MKH da trn mi kt hp bc 1 v cc loi thc th.*Xem
MKH bc 1 nh l loi thc th th bc 2 xem xt nhbc 1. Vd5? Vd6? Vd7? Vd8?
Vd9? Vd10? 39 3.5 M hnh Thc th kt hp m rng. 3.5.1 Loi Mi kt hp qui:
*Lloimikthpgiahailoi thc th trng nhau. V d: *Mikthpquilmikt hp gia
2 thc th ca cng mt loi thc th. Vid:1Thcth->LA,Long An,
QuanhngnghaLanggiengvi1thcth->HCM,HCh Minh,tothnhMKHLang gieng.
Gi tr ca MKH lng ging l: LA, HCM. V d 1: Xc nh ng ngha ca cc loi
MKH quy gia cc loi thc th sau: MnHc, ChanDua, NhaVien. V d 2:? 1
MKh hn th? Tinh_Tp Langgieng Ma_T_tp- Ten_Tp- Dt- Ds- (1,n) -? -?
40 3.5 M hnh Thc th kt hp m rng. 3.5.2 Loi mi kt hp nh ngha trn mt
loi MKH khc. Loi MKH bc 1: Loi MKH gia cc loi thc th. * Loi MKH bc
1, 2 ngi: Loi MKH gia cc 2 loi thc th. * Loi MKH bc 1, 3 ngi: Loi
MKH gia cc 3 loi thc th. Loi MKH bc 2: Loi Mkh gia loi MKH bc 1 vi
cc loi thc th. Cp bn s ca loi MKH bc 1 tham gia vo MKHbc 2 ging nh
loi thc th tham gia vo MKH bc 1. Biu din: MKH bc 1, 3 ngi MKHbc 2
Mikt hp bc n? Vd1: MKh bc 1, 3 ngi gia cc loi thc th: GV, Mon, Lop?
Vd2: MKh bc 2gia cc loi thc th: GV, Mon, Lop? Nhn xt vd1, vd2? Vd3:
MKh bc 2gia cc loi thc th: Phong, Lop, GV, Thu, ca, Mon? Vd4: MKh
bc 2gia cc loi thc th: Tran, CauThu, PhuT? VD 5? SVa tnh hung? Vui
ci: Anh Bnh,Anh Tho v c Vn t nm 1 ti nm 3 h chi thn vi nhau nh 3
ngi bn thn l MKH bc 1,3 ngi. Ti nm th 4, Anh Tho v c Vn hnh thnh
MKHxc nh ring tc bit v viMKH xem anh Bnh nhngi bn chung. Anh Bnh
thng hay ngm nga bi Mt ngi i vi mt ngi,mt ngi lng l AB ABC C (?,?)
(?,?) (?,?) A AB ABC B C (?,?) (?,?) (?,?) (?,?) 41 3.5 M hnh Thc
th kt hp m rng. 3.5.3Bn s ca mtloi MKH. Loi MKH thng thng c bn s l:
[1,1..1]. Ngha l mi biu hin ca1loiMKHltngbiuhin ca cc loi thc th
tham gia. LoiMKHmrngcbnsl: [1,1..1]. Ngha l 1 th hin ca MKH c th c
nhiu gi tr mt thuc tnh ca 1 thc th no . V d: Bn s MKH Loi MKH khi
chuyn thnh l quan h (hay loi quan h) th b vi phm DC1? Tm cch khc m
hnh ny? L quan h xe vi phm dc1? khc phc? Vn gi 3 loi thc th trn hy
iu chnh loi MKH c bn s[1,1..1]. Sv nu cc vd khc? SnMy Bnh xe
(0,1)(0,1) (0,1) [1,1,2] 42 3.5 M hnh Thc th kt hp m rng.
3.5.4Chuyn bit ha v tng qut ha. V d: Khi ci t c chuyn thnh l quan
h? Chuyn bit ha nhn vin ca trng H? Chuyn bit ha nhn vin ca nh my?
SV t a cc vd v chuyn bit ha, ch cc thuc tnh TQH v CB? TQH CB1CB2
NhanVien ThuKyCanBo MSNV- HoTen- NgayS- Phi- Tm--TN 43 3.5 M hnh
Thc th kt hp m rng. 3.5.5 Gia hai loi thc thcnhiuloiMKH,
MiloiMKHcmt ng ngha duy nht. Tm cc loi MKH gia cc loi thc th sau:
*vd1: KhachHang-PhieuGoiHang? *vd 2: NhanVien-Pban? *vd 3:
Nhanvien-Dchi? SV xut cc vd? AB MKH1 MKH2 MKH3 (?,?) (?,?) (?,?)
(?,?) (?,?) (?,?) 44 Bi c thm: Nhng kh khn khi xy dng m hnh QN DL
(i) Xem l loi thc th hay l loi MKH. * S nhm ln l do tn gi. V d xem
H l i tng qun l lc t, t t th n l loi thc th, nhng xem H l mi quan h
ca khch hng, mt hng, gi mt hng vi ngay t c th th n l loi MKH. *Nhn
theo nhn cc thnh phn l thuc tnh c lp th n l loi thc th, nhn theo
duyn cc thnh phn l MKH ca cc loi thc th. Giy kt hn l nhn nhng kt hn
li l duyn. nhn ch duyn.* S nhm ln thng do loi thc th c tnh tru tng
cao, Tnh tru tng c nng ln do tnh cht c lp ca thi gian, thi im. V d:
HoaDon, PhiuKB, GiyKS, SoHK. v.v
Vi d 1: Xem H l loi thc th? Vi d 2: M t loi MKH H? Nhn xt t vd1,
vd2? Cc v d do SV trnh by? 45 (ii)Xemnlthuctnhcaloithcth hay loi
thc.*Nhmlnldotngivloithc th c 1 thuc tnh trng tn vi tn ca loi thc
th. Vd:Trecthuctnhlngykhm hay khng c thuc tnh ngykhm th
cquanhngnghaviloithc thngykhm.Mckhcnhaul cch thc qun l: Loi thc th:
Loi MKH: (iii)Loithcthngytntikhng c t nhin, nhng vn ng!. (iV) MKH
bc 2 rt kh nhn bit!. Bi ton kh dn nu c bc 3,4 Vd1:XemPhongBanlloi
thc th? Vd2:XemPhongBanlthuc tnhcaloithcthnhn vin?Nunhtrongloithc
thnhnvinc2thuctnh l MPB, TenPB? Khinthuctnhcthquan h vi loi thc th
khc ? Mt a b cn nh xem nh mtthuctnhcaloithc thgianh.Khinlnc
nhngnhiuthuctnhring thaycMKHcnhnth phitchnraxemnhmt loi thc th?-Tch
h? Kh khn SV? Tre MSTRe- HoTen- NgaySinh- NgyKhm- Tre NgayKHam
MSTRe- HoTen- NgaySinh- -NgyKhm Co (1,n)(1,n) Bi c thm: Nhng kh khn
khi xy dng m hnh QN DL 46 Chng 4: M hnh Quan h d liu 4.1 Khi nim:
*Nhn thc DL mc logic. *M hnh logic DL. *Mc t chc DL sao cho gn gi
vi ci t. 4.2 u im ca MH: *Gn gi vi ngi SD v s dng
MHQHlMHbngDLrtthng dng trong i thng. *Rtdkhaithctheotruyvn ca Ngn
ng: -i S vi t duyrt logic, tng minh v cht ch.-NgnngSQLgngivi Ngn ng
t nhin v hu ht cc h qun tr u s dng. *DkimtraRBTV(ccquitc qun l) *D
dng kim tra vic chun ha (Mc trng lp thng tin). Mi tng quan gia qu
trnh nhn thc vi cc thnh phn HTTT? M hnh QH DL l kin ca mi tng quan
g? Ti sao gi l mc t chc DL. Vd1: DL bng? Vd 2: ng dng ca cuc sng i
vi cc php ton S: Chn, Chiu v Kt.Vn dng ti u ha truy vn s dng u tin
ca cc php ton trong cuc sng i thng? Vd3: Vn dng vic ti u trong tuyn
chn nhn s? Vd4: Nu 1 RBTV theo Ngn ng S. Nhc li dng chun? 47
4.3CcbcchuyntMHQNDLsangMH QH: 4.3.1Bc1:Chuynloithcththnh loi quan
h: *Thuctnhcaloithcththnh thuc tnh ca loi QH. *Khacaloithcththnhkha
ca loi QH.*Cc tnh hung c bit cn lu l loithcthtrongtrnghpchuynbit
ha-Tng qut ha: (i). S thuc tnh mc Chuyn Bitn
