Ngon Ngu SQL

L ngn ng chun truy vn v thao tc trnCSDL quan h

L ngn ng phi th tc

1. Gii thiu

3

L ngn ng phi th tc Khi ngun ca SQL l SEQUEL - Structured

English Query Language, nm 1974) Cc chun SQL

SQL89 SQL92 (SQL2) SQL99 (SQL3)

2. Cc ngn ng giao tip

Ngn ng nh ngha d liu (Data DefinitionLanguage - DDL): cho php khai bo cu trc bng,cc mi quan h v cc rng buc.

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Ngn ng thao tc d liu (Data ManipulationLanguage - DML): cho php thm, xa, sa d liu.

Ngn ng truy vn d liu (Structured QueryLanguage SQL): cho php truy vn d liu.

Ngn ng iu khin d liu (Data ControlLanguage DCL): khai bo bo mt thng tin, cp quyn v thu hi quyn khai thc trn c s d liu.

3.1 Lnh to bng (CREATE)3.1.1 C php3.1.2 Mt s kiu d liu3.1.3 Cc rng buc

3. Ngn ng nh ngha d liu

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3.1.3 Cc rng buc3.2 Lnh sa cu trc bng (ALTER)

3.2.1 Thm thuc tnh3.2.2 Sa kiu d liu ca thuc tnh3.2.3 Xo thuc tnh3.2.4 Thm rng buc ton vn3.2.5 Xo rng buc ton vn

3.3 Lnh xa bng (DROP)

3.1.1 C phpCREATE TABLE (

3.1 Lnh to bng

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[not null], [not null],

[not null],khai bo kha chnh, kha ngoi, rng buc)

To bng vi mt rng buc duy nhtC php:

CREATE TABLE

3.1 Lnh to bng (2)

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( [not null], [not null], [default gi_tr] [not null],[ CONSTRAINT PK_Tnbng_tnct PRIMARY

KEY(Danh_sch_ct_kha_chnh) ][CONSTRAINT UQ_Tnbng_tnct

UNIQUE(Danh_sch_cc_ct)])

V d:Create Table NhanVien( Manv int,

Hoten varchar (100) not null,

3.1 Lnh to bng (3)

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Hoten varchar (100) not null,Gioitinh varchar (5) default Nam,Cmnd varchar (10) not null,Mapb varchar (5),CONSTRAINT PK_Nhanvien_manv PRIMARYKEY(Manv) ,CONSTRAINT UQ_Nhanvien_cmndUNIQUE(Cmnd)

)

Lnh to bng vi rng buc kha ngoiC php:

CREATE TABLE

3.1 Lnh to bng (4)

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( [not null], [not null], [default gi_tr] [not null],[ CONSTRAINT FK_Tnbng_tnct FOREIGN

KEY(Danh_sch_kha_ngoi) REFERENCES Tn_bng_tham_chiu(Danh_sch_ct_tham_chiu)]

)

To bng vi rng buc kha ngoi, min gi trC php:

CREATE TABLE

3.1 Lnh to bng (5)

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( [not null], [not null], [default gi_tr][not null],[ CONSTRAINT FK_Tnbng_Tnct FOREIGN

KEY(Tnct_kha_ngoi) REFERENCES Tn_bng_tham_chiu (Tn_ct_tham_chiu)]

[ CONSTRAINT CK_Tnbng_tnct CHECK(Biu_thc_lun_l)]

)

Kiu d liu SQL Server

3.1 Lnh to bng (6)

3.1.2 Mt s kiu d liu

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Chui k t varchar(n), char(n),nvarchar(n), nchar(n)S tinyint, smallint, int,

numeric(m,n), decimal(m,n),float, real, smallmoney, money

Ngy thng smalldatetime, datetime

Lun l bit

Mt s kiu d liu (tt)Kiu d liu Kch

thcMin gi tr d liu lu tr

Cc kiu d liu dng s nguyn

Int 4 bytes t-2,147,483,648n +2,147,483,647

SmallInt 2 bytes t -32768 n +32767

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SmallInt 2 bytes t -32768 n +32767

TinyInt 1 byte t 0 n 255

Bit 1 byte 0, 1 hoc Null

Cc kiu d liu dng s thp phn

Decimal,Numeric

17bytes t -10^38 n +10^38

Cc kiu d liu dng s thc

Float 8 bytes t -1.79E+308 n +1.79E+308

Real 4 bytes t -3.40E+38 n +3.40E+38

Cc kiu d liu dng chui c di c nh

Char N bytes t 1 n 8000 k t, mi k t l mt

Mt s kiu d liu (tt)

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Char N bytes t 1 n 8000 k t, mi k t l mtbyte

Cc kiu d liu dng chui c di bin i

VarChar N bytes t 1 n 8000 k t, mi k t l 1byte

Text N bytes t 1 n 2,147,483,647 k t, mi kt l 1 byte

Cc kiu d liu dng tin t

Money 8 bytes t -922,337,203,685,477.5808 n+922,337,203,685,477.5807

SmallMoney 4 bytes t -214,748.3648 n +214,748.3647

Mt s kiu d liu (tt)

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214,748.3647

Cc kiu d liu dng ngy v gi

DateTime 8 bytes t01/01/1753n31/12/9999

SmallDateTime 4 bytes t01/01/1900n06/06/2079

Cc kiu d liu dng chui nh phn (Binary String)

Binary N bytes t 1 n 8000 bytes

VarBinary N bytes t 1 n 8000 bytes

Image N bytes t 1 n 2,147,483,647bytes

3.1 Lnh to bng (7)

3.1.3 Cc rng buc CHECK: quy nh cc gi tr d liu c php chp nhn

trn cc ct ca bng;

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trn cc ct ca bng; DEFAULT: Quy nh gi tr mc nh cho cc ct;

Ex: SoLuong int DAFAULT (0) PRIMARY KEY, UNIQUE, FOREIGN: To tnh ton vn

trong 1 bng d liu v ton vn tham chiu gia cc bngtrong CSDL.

3.1 Lnh to bng (8)

Lc CSDL qun l bn hng gm c cc quan h sau:

KHACHHANG (MAKH, HOTEN, DCHI, SODT, NGSINH,

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KHACHHANG (MAKH, HOTEN, DCHI, SODT, NGSINH, DOANHSO, NGDK, CMND)

NHANVIEN (MANV,HOTEN, NGVL, SODT, DIACHI)SANPHAM (MASP,TENSP, DVT, NUOCSX, GIA)HOADON (SOHD, NGHD, MAKH, MANV, TRIGIA)CTHD (SOHD,MASP,SL)

3.1 Lnh to bng (9)Create table KHACHHANG(

MAKH char(4) primary key,

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HOTEN varchar(40),DCHI varchar(50),SODT varchar(20),NGSINH smalldatetime,DOANHSO money,NGDK smalldatetime,CMND varchar(10)

)

3.1 Lnh to bng (10)

Create table CTHD(

SOHD int foreign key

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SOHD int foreign keyreferences HOADON(SOHD),

MASP char(4) foreign keyreferences SANPHAM(MASP),

SL int,constraint PK_CTHD primary key (SOHD,MASP)

)

3.1 Lnh to bng (11)Create table NHANVIEN(

MANV char (4) primary key,

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MANV char (4) primary key,HOTEN char (20),NGVL smalldatetime(),SODT char (8) null

constraint CHK_SoDT check SoDT like [0-9] [0-9] [0-9] [0-9] [0-9] [0-9] [0-9] [0-9]

DIACHI char (50) DEFAULT Khng bit)

3.2.1 Thm thuc tnhALTER TABLE tnbng ADD tnct kiudliu V d: thm ct Ghi_chu vo bng khch hng

ALTER TABLE KHACHHANG ADD GHI_CHU varchar(20)

3.2 Sa cu trc bng(1)

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ALTER TABLE KHACHHANG ADD GHI_CHU varchar(20)3.2.2 Sa kiu d liu thuc tnh

ALTER TABLE tnbng ALTER COLUMN tnct kiudliu_mi

Lu :Khng phi sa bt k kiu d liu no cng c

V d: Sa Ct Ghi_chu thnh kiu d liu varchar(50)ALTER TABLE KHACHHANG ALTER COLUMN GHI_CHU varchar(50) Nu sa kiu d liu ca ct Ghi_chu thnh varchar(50),

m trc nhp gi tr cho ct Ghi_chu c di hn


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m trc nhp gi tr cho ct Ghi_chu c di hn50 k t th khng c php.

Hoc sa t kiu chui k t sang kiu s, 3.2.3 Xa thuc tnh

ALTER TABLE tn_bng DROP COLUMN tn_ct V d: xa ct Ghi_chu trong bng KHACHHANG

ALTER TABLE NHANVIEN DROP COLUMN Ghi_chu

3.2.4 Thm rng buc ton vnUNIQUE tn_ct

PRIMARY KEY (tn_ct)


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ALTER TABLE ADD CONSTRAINT

PRIMARY KEY (tn_ct)FOREIGN KEY (tn_ct)REFERENCES tn_bng (ct_l_kha_chnh)CHECK (tn_ct iu_kin)

V d: ALTER TABLE NHANVIEN ADD CONSTRAINT

PK_NV PRIMARY KEY (MANV)


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ALTER TABLE CTHD ADD CONSTRAINT FK_CT_SP FOREIGN KEY (MASP) REFERENCES SANPHAM(MASP)

ALTER TABLE SANPHAM ADD CONSTRAINTCK_GIA CHECK (GIA >=500)

ALTER TABLE KHACHHANG ADD CONSTRAINTUQ_KH UNIQUE (CMND)

3.2.5 Xa rng buc ton vnALTER TABLE tn_bng DROP CONSTRAINT

tn_rng_buc


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tn_rng_buc V d:

Alter table CTHD drop constraint FK_CT_SP Alter table SANPHAM drop constraint ck_gia

Lu : i vi rng buc kha chnh, mun xarng buc ny phi xa ht cc rng buc khangoi tham chiu ti n

C phpDROP TABLE tn_bng

V d: xa bng KHACHHANG.

3.3 Lnh xa bng

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V d: xa bng KHACHHANG.DROP TABLE KHACHHANG

Lu : khi mun xa mt bng phi xa tt c nhng kha ngoi tham chiu ti bng trc.

Gm cc lnh: 4.1 Lnh thm d liu (INSERT)4.2 Lnh sa d liu (UPDATE)

4. Ngn ng thao tc d liu

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4.2 Lnh sa d liu (UPDATE)4.3 Lnh xa d liu (DELETE)

C phpINSERT INTO tn_bng (ct1,,ctn) VALUES

(gi_tr_1,., gi_tr_n)INSERT INTO tn_bng VALUES (gi_tr_1,

4.1 Thm d liu

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INSERT INTO tn_bng VALUES (gi_tr_1,gi_tr_2,, gi_tr_n)

V d insert into SANPHAM values('BC01','But chi', 'cay',

'Singapore', 3000) insert into SANPHAM(masp,tensp,dvt,nuocsx,gia)

values ('BC01','But chi','cay','Singapore',3000)

C phpUPDATE tn_bngSET ct_1 = gi_tr_1, ct_2 = gi_tr_2 .[WHERE iu_kin]

4.2 Sa d liu

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[WHERE iu_kin] Lu : cn thn vi cc lnh xa v sa, nu khng

c iu kin WHERE ngha l xa hoc sa tt c. V d: Tng gi 10% i vi nhng sn phm do

Trung Quoc sn xutUPDATE SANPHAMSET Gia = Gia*1.1WHERE Nuocsx=Trung Quoc

4.3 Xa d liu

C phpDELETE FROM tn_bng [WHERE iu_kin]

V d:

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V d: Xa ton b nhn vin

DELETE FROM NHANVIEN Xa nhng sn phm do Trung Quc sn xut c gi

thp hn 10000DELETE FROM SANPHAM WHERE (Gia

5. Ngn ng truy vn d liu c cu trc

5.1 Cu truy vn tng qut 5.2 Truy vn n gin5.3 Php kt

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5.3 Php kt5.4 t b danh, s dng *, distinct5.5 Cc ton t5.6 Cu truy vn con (subquery)5.7 Php chia5.8 Hm tnh ton, gom nhm

SELECT [DISTINCT] *|tn_ct | hmFROM bng [WHERE iu_kin]

5.1Cu truy vn tng qut

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[WHERE iu_kin][GROUP BY tn_ct][HAVING iu_kin][ORDER BY tn_ct ASC | DESC]

5.2 Truy vn n gin(1) SELECT

Tng ng php chiu ca SQH Lit k cc thuc tnh cn hin th trong kt qu

WHERE

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L iu kin chn trong SQH iu kin lin quan ti thuc tnh, s dng cc php ni

lun l AND, OR, NOT, cc php ton so snh, BETWEEN FROM

Lit k cc quan h cn thit. L php tch Decartes cc quan h (khng c t kha

JOINT, ch l du phy gia cc quan h). L php kt cc quan h (nu c t kha JOINT)

5.2 Truy vn n gin(2)

Tm masp, tensp do Trung Quoc sn xut c gi t 20000 n 30000

Select masp,tensp

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Select masp,tenspFrom SANPHAMWhere nuocsx=Trung Quoc

and gia between 20000 and 30000

5.3 Php kt(1)

Inner Join, Left Join, Right Join, Full Join V d:

In ra danh sch cc khch hng (MAKH,

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In ra danh sch cc khch hng (MAKH, HOTEN) mua hng trong ngy 1/1/2007.select KHACHHANG.makh,hoten from KHACHHANG inner join HOADON on

KHACHHANG.makh=HOADON.makh where nghd='1/1/2007'

5.3 Php kt (2)

V d: In ra danh sch tt c cc ha n v h tn ca khch hng mua ha n (nu c) Select sohd, hoten

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Select sohd, hotenFrom HOADON left join KHACHHANG on

HOADON.makh=KHACHHANG.makh Select sohd, hoten

From HOADON, KHACHHANG where HOADON.makh*=KHACHHANG.makh

5.4 t b danh, s dng *, distinct

t b danh Alias: cho thuc tnh v quan h: tn_c AS tn_mi Select manv,hoten as [ho va ten] From NHANVIEN

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Lit k tt c cc thuc tnh ca quan h: Select * from Nhanvien Select NHANVIEN.* from NHANVIEN

Distinct: trng ch ly mt ln Select distinct nuocsx from SANPHAM

Sp xp kt qu hin th: Order by Select * from SANPHAM order by nuocsx, gia DESC

5.5 Ton t truy vn(1)

Ton t so snh: =, >,=,

5.5 Ton t truy vn(2) IS NULL, IS NOT NULL

Select sohd from HOADON where makh is Null Select * from HOADON where makh is Not Null

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Ton t so snh, php ton Select gia*1.1 as [gia ban] from SANPHAM where nuocsx

Viet Nam Select * from SANPHAM where (gia between 20000 and

30000) OR (nuocsx = Viet Nam) Ton t IN, NOT IN: Cc mu tin ca query chnh c

gi tr bng vi mt gi tr trong subquery Select * from SANPHAM where masp NOT IN

(BB01,BB02,BB03)

Ton t LIKE

So snh chui tng i

C php: s LIKE p, p c th cha % hoc _

5.5 Ton t so snh(3)

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C php: s LIKE p, p c th cha % hoc _

% : thay th mt chui k t bt k _ : thay th mt k t bt k V d: Select masp,tensp from SANPHAM

where masp like 'B%01

5.6 Cu truy vn con (0) Exists: c s dng kt hp vi truy vn con di dng:

WHERE [NOT] EXISTS (truy_vn_con) kim tra xem 1 truy vn con c tr v dng kt qu no hay

khng. Lng t EXISTS (tng ng NOT EXISTS) tr v gi tr True nu kt qu ca truy vn con c t nht mt dng

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(tng ng khng c dng no). iu khc bit ca vic s dng EXISTS vi hai cch nu trn l trong danh sch chn ca truy vn con c th c nhiu hn hai ct.

V d: Cho bit h tn sinh vin cha c im thi ca bt k mn hc no.

5.6 Cu truy vn con (1)In hoc Exists (Cc mu tin ca query chnh tha mn khi subquery c mu tin)

V d: Tm cc s ha n mua cng lc 2 sn phm c m s BB01 v BB02.

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BB01 v BB02. select distinct sohd

from CTHD where masp='BB01' and sohd IN(select distinct sohd from CTHD where masp='BB02')

select distinct A.sohd from CTHD A where A.masp='BB01' and

EXISTS (select * from CTHD B where B.masp='BB02' and A.sohd=B.sohd)

5.6 Cu truy vn con (2)

Not In hoc Not Exists V d: Tm cc s ha n c mua sn phm m s

BB01 nhng khng mua sn phm m s BB02.

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BB01 nhng khng mua sn phm m s BB02. select distinct sohd

from CTHD where masp='BB01' and sohd NOT IN(select distinct sohd from CTHD where masp='BB02')

select distinct A.sohd from CTHD A where A.masp='BB01' and

NOT EXITST (select * from CTHD B where B.masp='BB02 and A.sohd=B.sohd)

5.7 Php chia

V d: Tm nhng sn phm ca Singapore mSoHD 1001 cha mua+ S dng NOT IN

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SELECT * FROM SANPHAMWHERE NUOCSX='SINGAPORE' AND MASP NOT IN(--Cu truy vn con

SELECT MASP FROM CTHDWHERE SOHD='1001')

5.7 Php chia (1)

V d: Tm nhng sn phm ca Singapore m SoHD 1001 cha mua + S dng NOT EXISTS

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+ S dng NOT EXISTSSELECT * FROM SANPHAM AWHERE NUOCSX='SINGAPORE' AND NOT EXISTS(--

Cu truy vn conSELECT * FROM CTHD BWHERE SOHD='1001' AND A.MASP=B.MASP)

5.7 Php chia

S dng NOT EXISTS V d: Tm s ha n mua tt c nhng sn

phm.

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phm.Select sohd from HOADON where not exists (select * from SANPHAM where not exists

(select * from CTHD where HOADON.sohd=CTHD.sohd and CTHD.masp=SANPHAM.masp))

5.7 Php chiaS dng NOT EXISTS V d: Tm s ha n mua tt c nhng sn

phm do Trung Quoc sn xut:Select sohd from HOADON where not exists

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Select sohd from HOADON where not exists (select * from SANPHAM where nuocsx=Trung Quoc and not exists

(select * from CTHD where HOADON.sohd=CTHD.sohd and CTHD.masp=SANPHAM.masp))

- Ph: tm nhng sn phm ca TQ m mt S ha n bt kcha mua. Ph: ng (khng c SP no) = S ha n mua tt c sn phm ca Trung Quc

5.8.1 Cc hm tnh ton c bn COUNT: m s b d liu ca thuc tnh

5.8 Cc hm tnh ton v gom nhm (1)

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MIN: Tnh gi tr nh nht

MAX: Tnh gi tr ln nht

AVG: Tnh gi tr trung bnh

SUM: Tnh tng gi tr cc b d liu

NHANVIEN

MANV HOTEN PHAI MANQL PHONG LUONGNV001 Nguyn Ngc Linh N Null NC 2.800.000

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NV002 inh B Tin Nam NV002 DH 2.000.000NV003 Nguyn Vn Mnh Nam NV001 NC 2.300.000NV004 Trn Thanh Long Nam NV002 DH 1.800.000NV005 Nguyn Th Hng Vn N NV001 NC 2.500.000NV006 Nguyn Minh Nam NV002 DH 2.000.000NV007 H Duy Lp Nam NV003 NC 1.800.000NV008 Trn Kim Duyn N NV003 NC 1.800.000NV009 Nguyn Kim Anh N NV003 NC 2.000.000

V d

1. Tnh lng thp nht, cao nht, trung bnh v tng lng ca tt c cc nhn vin.

2. C tt c bao nhiu nhn vin

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2. C tt c bao nhiu nhn vin3. Bao nhiu nhn vin c ngi qun l4. Bao nhiu phng ban c nhn vin trc thuc5. Tnh lng trung bnh ca cc nhn vin6. Tnh lng trung bnh ca cc nhn vin theo

tng phng ban

1. Tnh lng thp nht, cao nht, trung bnh v tng lng ca tt c cc nhn vin.

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SELECT min(luong) as thapnhat, max(luong) as caonhat, avg(luong) as trungbinh, sum(luong) as tongluong

FROM NhanVien

2. C tt c bao nhiu nhn vinSELECT count(*) FROM NhanVien

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3. Bao nhiu nhn vin c ngi qun l Select count(*) FROM NhanVien WHERE manql is not null SELECT count(Manql) FROM NhanVien

4. Bao nhiu phng ban c nhn vin trc thucSELECT count(distinct phong) FROM NhanVien


5.8.2 Gom nhm: mnh GROUP BY S dng hm gom nhm trn cc b trong quan h. Mi nhm b bao gm tp hp cc b c cng gi tr trn

52

Mi nhm b bao gm tp hp cc b c cng gi tr trn cc thuc tnh gom nhm

Hm gom nhm p dng trn mi b c lp nhau. SQL c mnh GROUP BY ch ra cc thuc tnh

gom nhm, cc thuc tnh ny phi xut hin trong mnh SELECT

5. Tnh lng trung bnh ca cc nhn vinSELECT avg(LUONG) as LUONGTBFROM NhanVien

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FROM NhanVien

6. Tnh lng trung bnh ca cc nhn vin theo tng phng ban.SELECT phong, avg(LUONG) as LUONGTBFROM NhanVienGROUP BY phong


5.8.3 iu kin sau gom nhm: mnh HAVING Lc kt qu theo iu kin, sau khi gom nhm iu kin HAVING c thc hin sau khi gom nhm,

54

iu kin HAVING c thc hin sau khi gom nhm, cc iu kin c lin quan n thuc tnh Group By

V d: tm phng c s lng nhn vin N trn 5 ngiSELECT phongFROM NhanVienWHERE phai = NGROUP BY phongHAVING count(manv) > 5

5.9 Cc hm x l trong SQL

Hm ton hc

55

Hm x l xu

Hm ngy thng

Hm chuyn i

Hm ton hc

Sqrt(n): cn bc 2 Square(n): hm bnh phng Sign(n): hm ly du

56

Sign(n): hm ly du Sign(10) = Sign(5) = 1, Sign(-2) = -1

Pi(): tr v gi tr Pi Round(n): lm trn Ceiling(n): lm trn ln Floor(n): lm trn xung

Hm x l xu Upper(str): chuyn i xu str sang ch HOA

Upper(H Ni) => H NI Lower(str) : chuyn i xu str sang ch thng

Lower(H Ni) => h ni

57

Len(str) : tr v di ca xu + : php ton ghp 2 xu

H Ni + H Nam => H NiH Nam

Ltrim(str) : loi b k t trng bn tri xu Ltrim( H Ni ) => H Ni

Rtrim(str) : loi b k t trng bn phi xu Rtrim( H Ni ) => H Ni

Hm x l xu Left(str,n) : tr v n k t bn tri xu

Left(H Ni,5) => H N Right(str,n) : tr v n k t bn phi xu

Left(H Ni,5) => Ni

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Left(H Ni,5) => Ni Substring(str,m,n) : tr v n k t bt u t v tr th m trong

xu str Subtring(H Ni,2,4) => N;

Replace(str,str1,str2) : thay th xu str1 bng xu str2 nu str1 xut hin trong str Replace(H Ni,Ni,Nam) => H Nam

Reverse(str) : tr v xu o ngc ca xu str Reverse(H Ni) => iN H

Hm ngy thng

Getdate(): hm tr ra ngy gi h thng Datepart(tham_s_datepart, date): tr v gi tr

nguyn theo tham s ly

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nguyn theo tham s ly

V dDatepart(dd,getdate());Datepart(yyyy,getdate());

Hm ngy thng Day(date) : tr v gi tr nguyn ngy Month(date) : tr v gi tr nguyn thng Year(date): tr v gi tr nguyn nm

Year(2007/5/20) => 2007

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Year(2007/5/20) => 2007

Datediff(tham_s_datepart, date1, date2): tr vkhong cch date2-date1 theo tham s Datediff(mm, 2006/5/15, 2007/10/15) => 17

Dateadd(tham_s_datepart, n, date): cng thm n theo loi tham s vo date Dateadd(dd, 40, 2007/5/15) => 2007/6/24

DDLDML SQLHm tnh

ton & x l

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ton & x l

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