Ch02-Ngon Ngu Truy Van SQL

CHNG 2CHNG 2NGN NG TRUY VN SQLNGN NG TRUY VN SQLNGN NG TRUY VN SQLNGN NG TRUY VN SQL

Ni dung chi tit

Gii thiu nh ngha d liu Cp nht d liu Truy vn d liu Mt s hm thng dng

2

Mt s hm thng dng

Gii thiu

SQL (Structured Query Language)- Ngn ng cp cao- Ngi s dng ch cn a ra ni dung cn truy vn- c pht trin bi IBM (1970s), c gi l SEQUEL

(Structured English Query Language)

3

- c ANSI cng nhn v pht trin thnh chun SQL-86 SQL-92 SQL-99

SEQUEL: Structured English Query LanguageANSI: American National Standards Institute

Gii thiu (tt)

SQL gm cc cu lnh cho php- nh ngha d liu DDL (Data Definition Language)- Thao tc d liu DML (Data Manipulation Language)- Rng buc ton vn- nh ngha khung nhn

4

- Phn quyn v bo mt-

SQL s dng thut ng- Bng ~ quan h- Ct ~ thuc tnh- Dng ~ b

Ni dung chi tit

Gii thiu nh ngha d liu

- Kiu d liu- Cc lnh nh ngha d liu

Truy vn d liu

5

Truy vn d liu Cp nht d liu Mt s hm thng dng

nh ngha d liu

L ngn ng m t- Lc cho mi quan h- Min gi tr tng ng ca tng thuc tnh- Rng buc ton vn- Ch mc trn mi quan h

6

Gm- CREATE TABLE (to bng)- DROP TABLE (xa bng)- ALTER TABLE (sa bng)- CREATE DATABASE-

Kiu d liu

S- SMALLINT- INT- NUMERIC- DECIMAL

7

- REAL- FLOAT- .

H? th?ng SQL h? tr? ki?u d? li?u l ki?u d? li?u co s? (Atomic)

Kiu d liu (tt)

Chui k t- CHAR, VARCHAR- NCHAR, NVARCHAR (g du ting Vit Unicode)-

Chui bit

8

Chui bit- BIT- BITINT-

Ngy gi- DATETIME- SMALLDATETIME

Lnh to bng

nh ngha mt bng- Tn bng- Cc thuc tnh

Tn thuc tnh Kiu d liu Cc RBTV trn thuc tnh

9

Cc RBTV trn thuc tnh

C php

CREATE TABLE ( [], [],[]

)

V d - To bng

CREATE TABLE NHANVIEN (

HONV NVARCHAR (20),

TENLOT NVARCHAR (50),

TENNV NVARCHAR (20),

MANV NVARCHAR (20),

NGSINH SMALLDATETIME,

10


DCHI NVARCHAR (50),

PHAI NVARCHAR (10),

LUONG INT,

MA_NQL NVARCHAR (20),

PHG INT

)

Lnh to bng (tt)

- NOT NULL- UNIQUE- DEFAULT- PRIMARY KEY

11

- FOREIGN KEY / REFERENCES- CHECK

t tn cho RBTV

CONSTRAINT

V d - To bng c RBTV

CREATE TABLE NHANVIEN (

HONV NVARCHAR (20) NOT NULL,

TENLOT NVARCHAR (50) NOT NULL,

TENNV NVARCHAR (20) NOT NULL,

MANV NVARCHAR (20) PRIMARY KEY,

12


DCHI NVARCHAR(50),

PHAI NVARCHAR(10) CHECK (PHAI IN (Nam, Nu)),

LUONG INT DEFAULT (1000000),

MA_NQL NVARCHAR(20),

PHG INT

)

V d - To bng c RBTV (tt)

CREATE TABLE PHONGBAN (

TENPHG NVARCHAR(40) UNIQUE,

MAPHG INT PRIMARY KEY,

TRPHG NVARCHAR(20),

NG_NHANCHUC SMALLDATETIME DEFAULT (GETDATE())

13

)

CREATE TABLE DIADIEM_PHG(

MAPHG INT NOT NULL,

DIADIEM NVARCHAR(50) NOT NULL,

CONSTRAINT PK_DIADIEM_PHG PRIMARY KEY (MAPHG , DIADIEM)

)

V d - To bng c RBTV (tt)

CREATE TABLE DEAN (

TENDA NVARCHAR(40) UNIQUE,

MADA INT PRIMARY KEY,

DDIEM_DA NVARCHAR(50),

PHONG INT

)

14

)

CREATE TABLE PHANCONG (

MA_NVIEN NVARCHAR(20) FOREIGN KEY (MA_NVIEN)

REFERENCES NHANVIEN(MANV),

SODA INT FOREIGN KEY (SODA)

REFERENCES DEAN(MADA),

THOIGIAN NUMERIC(3,1)

)

V d - t tn cho RBTVCREATE TABLE NHANVIEN (

HONV NVARCHAR(20) CONSTRAINT NV_HONV_NN NOT NULL,

TENLOT NVARCHAR(50) NOT NULL,

TENNV NVARCHAR(20) NOT NULL,

MANV NVARCHAR(20) CONSTRAINT NV_MANV_PK PRIMARY KEY,


15


DCHI NVARCHAR(50),

PHAI NVARCHAR(10) CONSTRAINT NV_PHAI_CHK

CHECK (PHAI IN (Nam, Nu)),

LUONG INT CONSTRAINT NV_LUONG_DF DEFAULT (10000),

MA_NQL NVARCHAR(20),

PHG INT

)

V d - t tn cho RBTV (tt)

CREATE TABLE PHANCONG (

MA_NVIEN NVARCHAR(20),

SODA INT,

THOIGIAN NUMERIC(3,1),

16

CONSTRAINT PC_MANVIEN_SODA_PK PRIMARY KEY (MA_NVIEN, SODA),

CONSTRAINT PC_MANVIEN_FK FOREIGN KEY (MA_NVIEN)


CONSTRAINT PC_SODA_FK FOREIGN KEY (SODA)

REFERENCES DEAN(MADA)

)

Lnh sa bng

Dng : thay i cu trc bng, thay i RBTV Thm ct

- V d

ALTER TABLE ADD []

ALTER TABLE NHANVIEN ADD NGHENGHIEP NVARCHAR(50)

17

Xa ct

- V d

ALTER TABLE NHANVIEN ADD NGHENGHIEP NVARCHAR(50)

ALTER TABLE DROP COLUMN

ALTER TABLE NHANVIEN DROP COLUMN NGHENGHIEP

Lnh sa bng (tt)

Hiu chnh ct

- V d

ALTER TABLE NHANVIEN ALTER COLUMN NGHENGHIEP NVARCHAR(70)

ALTER TABLE ALTER COLUMN

18

ALTER TABLE NHANVIEN ALTER COLUMN NGHENGHIEP NVARCHAR(70)

Lnh sa bng (tt)

Thm RBTV

- V d

ALTER TABLE ADDCONSTRAINT ,

CONSTRAINT ,

19

- V dALTER TABLE PHONGBAN ADD

CONSTRAINT PB_MAPHG_PK PRIMARY KEY (MAPHG),

CONSTRAINT PB_TRPHG FOREIGN KEY (TRPHG)


CONSTRAINT PB_NGNHANCHUC_DF DEFAULT (GETDATE())

FOR NG_NHANCHUC,

CONSTRAINT PB_TENPB_UNI UNIQUE (TENPB)

Lnh sa bng (tt)

Xem cc RBTV

- V d

Xa RBTV

SP_HELPCONSTRAINT

SP_HELPCONSTRAINT PHONGBAN

20

Xa RBTV

- V d

ALTER TABLE DROP

ALTER TABLE PHONGBAN DROP PB_MAPHG_PK

ALTER TABLE PHONGBAN DROP PB_TRPHG

ALTER TABLE PHONGBAN DROP PB_NGNHANCHUC_DF

ALTER TABLE PHONGBAN DROP PB_TENPB_UNI

Lnh xa bng

c dng xa cu trc bng- Tt c d liu ca bng cng b xa

C php

DROP TABLE

21

V d

DROP TABLE

DROP TABLE NHANVIEN

DROP TABLE PHONGBAN

DROP TABLE PHANCONG

Lnh xa bng (tt)

NHANVIEN

TENNVHONV TENLOT MANV NGSINH DCHI PHAI LUONG MA_NQL PHG

22

PHONGBAN

TRPHGTENPHG MAPHG NG_NHANCHUC

Lnh to kiu d liu mi

To ra mt kiu d liu mi k tha nhng kiu dliu c sn

C php

- V dCREATE TYPE FROM

23

- V d

Xa kiu d liu t nh ngha

- V d

CREATE TYPE Kieu_Ten FROM NVARCHAR(30)

DROP TYPE

DROP TYPE Kieu_Ten

S dng DEFAULT v RULE

Default v Rule l i tng c th kt vi mt hocnhiu ct- To Default

- Rng buc Default vo ct

CREATE DEFAULT AS

24

- G b Default khi ct

- V dCREATE DEFAULT NV_LUONG_DF AS 10000

sp_bindefault NV_LUONG_DF, NHANVIEN.LUONG

sp_unbindefault NHANVIEN.LUONG

sp_bindefault ,

sp_unbindefault

S dng DEFAULT v RULE (tt)

- To Rule

- Rng buc Rule vo ct

- G b Rule khi ct

CREATE RULE AS

sp_bindrule < Tn_rule >,

sp_unbindrule

25

- V d

- Xa Defaule, Rule

CREATE RULE R_LUONG AS @LUONG>=10000

sp_bindrule R_LUONG , NHANVIEN.LUONG

sp_unbindrule NHANVIEN.LUONG

sp_unbindrule

DROP DEFAULT

DROP RULE

DROP DEFAULT NV_LUONG_DF

DROP RULE R_LUONG

Ni dung chi tit

Gii thiu nh ngha d liu Cp nht d liu

- Thm (insert)- Xa (delete)

26

- Xa (delete)- Sa (update)

Truy vn d liu Mt s hm thng dng

Lnh INSERT

Dng thm 1 hay nhiu dng vo bng

thm d liu- Tn bng- Danh sch cc thuc tnh cn thm d liu

27

- Danh sch cc thuc tnh cn thm d liu- Danh sch cc gi tr tng ng

C php (thm 1 dng)

INSERT INTO [()]

VALUES ()

V d

INSERT INTO NHANVIEN(HONV, TENLOT, TENNV, MANV)

VALUES (NNguyn, NTrng, NHa, 123)

INSERT INTO NHANVIEN(HONV, TENLOT, TENNV, MANV, DCHI)

28

INSERT INTO NHANVIEN

VALUES (NTrn, NThanh, NTm, 453, 7/31/1962, NMai Th Lu, Nam, 25000,333,5)

INSERT INTO NHANVIEN(HONV, TENLOT, TENNV, MANV, DCHI)

VALUES ( NNguyn, NThanh, NTng, 333, NULL)

Lnh INSERT (tt)

Nhn xt- Th t cc gi tr phi trng vi th t cc ct

- C th thm gi tr NULL nhng thuc tnh khng lkha chnh v cho php NULL

29

- Cu lnh INSERT s gp li nu vi phm RBTV Kha chnh Tham chiu NOT NULL - cc thuc tnh c rng buc NOT NULL bt buc

phi c gi tr

Lnh INSERT (tt)

C php (thm nhiu dng)

INSERT INTO [()]

30

V d

CREATE TABLE THONGKE_PB (

TENPHG NVARCHAR(20),

SL_NV INT,

LUONG_TC INT

)

31

INSERT INTO THONGKE_PB(TENPHG, SL_NV, LUONG_TC)

SELECT TENPHG, COUNT(MANV), SUM(LUONG)

FROM NHANVIEN, PHONGBAN

WHERE PHG=MAPHG

GROUP BY TENPHG

Lnh DELETE

Dng xa cc dng ca bng

C php

DELETE FROM

32

DELETE FROM

[WHERE ]

V d

DELETE FROM NHANVIEN

WHERE HONV=Tran


33


WHERE MANV=333


Lnh DELETE (tt)

Nhn xt- S lng s dng b xa ph thuc vo iu kin

mnh WHERE

- Nu khng ch nh iu kin mnh WHERE, tt ccc dng trong bng s b xa

34

cc dng trong bng s b xa

- Lnh DELETE c th gy ra vi phm RB tham chiu Khng cho xa Xa lun nhng dng c gi tr ang tham chiu n

CASCADE

t NULL cho nhng gi tr tham chiu

Lnh DELETE (tt) TENNVHONV NGSINH DCHI PHAI LUONG PHG

TungNguyen 12/08/1955 638 NVC Q5 Nam 40000 5

HungNguyen 09/15/1962 Ba Ria VT Nam 38000 5

333445555

987987987

MANV MA_NQL

888665555

333445555

TENLOT

Thanh

Manh

HangBui 07/19/1968 33 NTH Q1 Nu 38000 4999887777 987654321Ngoc

NhuLe 07620/1951 219 TD Q3 Nu 43000 4987654321 888665555Quynh

TamTran 07/31/1972 543 MTL Q1 Nu 25000 5453453453 333445555Thanh

QuangTran 04/08/1969 980 LHP Q5 Nam 25000 4987987987 987654321Hong

35

VinhPham 11/10/1945 450 TV HN Nam 55000 1888665555 NULLVan

SODA THOIGIANMA_NVIEN

10 10.0333445555

20 20.0888665555

30 20.0987654321

1 20.0453453453

10 35.0987987987

30 5.0987987987

Lnh DELETE (tt)

05/22/1988333445555Nghien cuu 5

NG_NHANCHUCMA_NVIEN

01/01/1995

06/19/1981

987987987

888665555

TENPHG MAPHG

Dieu hanh 4

Quan ly 1

36

TENNVHONV NGSINH DCHI PHAI LUONG PHG

TungNguyen 12/08/1955 638 NVC Q5 Nam 40000

HungNguyen 09/15/1962 Ba Ria VT Nam 38000

333445555

987987987

MANV MA_NQL

888665555

333445555

TENLOT

Thanh

Manh

HangBui 07/19/1968 33 NTH Q1 Nu 38000 4999887777 987654321Ngoc


VinhPham 11/10/1945 450 TV HN Nam 55000 1888665555 NULLVan

TamTran 07/31/1972 543 MTL Q1 Nu 25000

5

5

5453453453 333445555Thanh

QuangTran 04/08/1969 980 LHP Q5 Nam 25000 4987987987 987654321Hong

NULL

NULL

NULL

Lnh UPDATE

Dng thay i gi tr ca thuc tnh cho cc dngca bng

C php

UPDATE

37

UPDATE

SET =,

=,

[WHERE ]

V d

UPDATE NHANVIEN

SET NGSINH=08/12/1965

WHERE MANV=333445555

38

UPDATE NHANVIEN

SET LUONG=LUONG*1.1

V d

Vi n c m s 10, hy thay i ni thc hin n thnh Vung Tau v phng ban ph trch lphng 5

UPDATE DEAN

39

UPDATE DEAN

SET DIADIEM_DA=Vung Tau, PHONG=5

WHERE MADA=10

Lnh UPDATE

Nhn xt- Nhng dng tha iu kin ti mnh WHERE s

c cp nht gi tr mi

- Nu khng ch nh iu kin mnh WHERE, tt ccc dng trong bng s b cp nht

40

cc dng trong bng s b cp nht

- Lnh UPDATE c th gy ra vi phm RB tham chiu Khng cho sa Sa lun nhng dng c gi tr ang tham chiu n

CASCADE

Ni dung chi tit

Gii thiu nh ngha d liu Cp nht d liu Truy vn d liu

- Truy vn c bn

41

- Truy vn c bn- Tp hp, so snh tp hp v truy vn lng- Hm kt hp v gom nhm- Mt s kiu truy vn khc

Mt s hm thng dng

Truy vn d liu

L ngn ng rt trch d liu tha mt s iu kinno

Da trn

Php ton SQH Mt s b sung++++

42

- Cho php 1 bng c nhiu dng trng nhau- Bng l bag quan h l set

Truy vn c bn

Gm 3 mnh

- Tn cc ct cn c hin th trong kt qu truy vn

-

SELECT

FROM

WHERE

43

- Tn cc bng lin quan n cu truy vn

- Php ton: +, -, *, /, % Php so snh: =, = , , != Php ton logic: and, or, not Php ton tp hp: all, any, in, like, between, exists

V d

SELECT *

FROM NHANVIEN

WHERE PHG=5

Ly tt c cc ct ca quan h kt qu

44




333445555

987987987

MANV MA_NQL

888665555

333445555

TENLOT

Thanh

Manh

Mnh SELECT

SELECT MANV, HONV, TENLOT, TENNV

FROM NHANVIEN

WHERE PHG=5 AND PHAI=Nam

45

TENNVHONV

TungNguyen

HungNguyen

TENLOT

Thanh

Manh

333445555

987987987

MANV

Mnh SELECT (tt)

SELECT MANV, HONV AS HO, TENLOT AS TEN LOT, TENNV AS TEN

FROM NHANVIEN


Tn b danh

46

TENHO

TungNguyen

HungNguyen

TEN LOT

Thanh

Manh

333445555

987987987

MANV

Mnh SELECT (tt)

SELECT MANV, HONV + + TENLOT + + TENNV AS HO TEN

FROM NHANVIEN


M rng

47

HO TEN

Nguyen Thanh Tung

Nguyen Manh Hung

333445555

987987987

MANV

Mnh SELECT (tt)

SELECT MANV, LUONG*1.1 AS LUONG10%

FROM NHANVIEN


M rng

48

LUONG10%

33000

27500

333445555

987987987

MANV

Mnh SELECT (tt)

SELECT LUONG

FROM NHANVIEN


Loi b cc dng trng nhau

SELECT DISTINCT LUONG

FROM NHANVIEN


49

LUONG

30000

25000

25000

38000

LUONG

30000

25000

38000

Mnh WHERE

SELECT MANV, TENNV


WHERE TENPHG=Nghien cuu AND PHG=MAPHG

Biu thc lun l

50


TRUE TRUE

Mnh WHERE (tt)

SELECT MANV, TENNV


u tin

51

WHERE (TENPHG=Nghien cuu OR TENPHG=Quan ly) AND PHG=MAPHG

Mnh WHERE (tt)

SELECT MANV, TENNV

FROM NHANVIEN

WHERE LUONG>=20000 AND LUONG=20000 AND LUONG

Mnh WHERE (tt)

NOT BETWEEN

SELECT MANV, TENNV

FROM NHANVIEN

53

FROM NHANVIEN

WHERE LUONG NOT BETWEEN 20000 AND 30000

Mnh WHERE (tt)

SELECT MANV, TENNV

FROM NHANVIEN

WHERE DCHI LIKE Nguyen _ _ _ _

LIKE

54

WHERE DCHI LIKE Nguyen _ _ _ _

SELECT MANV, TENNV

FROM NHANVIEN

WHERE DCHI LIKE Nguyen %

Chui bt k

K t bt k

Mnh WHERE (tt)

SELECT MANV, TENNV

FROM NHANVIEN

WHERE HONV LIKE Nguyen

NOT LIKE

55

WHERE HONV LIKE Nguyen

SELECT MANV, TENNV

FROM NHANVIEN

WHERE HONV NOT NOT LIKE Nguyen

Mnh WHERE (tt)

Ngy gi

SELECT MANV, TENNV

FROM NHANVIEN

WHERE NGSINH BETWEEN 12/8/1955 AND 7/19/1966

56

WHERE NGSINH BETWEEN 12/8/1955 AND 7/19/1966

Mnh WHERE (tt)

NULL

SELECT MANV, TENNV

FROM NHANVIEN

WHERE MA_NQL IS NULL

57

SELECT MANV, TENNV

FROM NHANVIEN

WHERE MA_NQL IS NOT NULL

WHERE TRUE

Mnh FROM

SELECT MANV, MAPHG


Khng s dng mnh WHERE

58

MAPHG

1

4

333445555

333445555

MANV

5

1987987987

987987987

333445555

4

5987987987

Mnh FROM (tt)

SELECT TENPHG, DIADIEM

FROM PHONGBAN, DDIEM_PHG

WHERE MAPHG=MAPHG

Tn b danh

SELECT TENPHG, DIADIEM

FROM PHONGBAN AS PB, DDIEM_PHG AS DD

WHERE PB.MAPHG=DD.MAPHG

59

WHERE MAPHG=MAPHGWHERE PB.MAPHG=DD.MAPHG

SELECT TENNV, NGSINH, TENTN, NGSINH

FROM NHANVIEN, THANNHAN

WHERE MANV=MA_NVIEN

SELECT TENNV, NV.NGSINH, TENTN, TN.NGSINH

FROM NHANVIEN NV, THANNHAN TN

WHERE MANV=MA_NVIEN

Mnh ORDER BY

Dng hin th kt qu cu truy vn theo mt tht no

C phpSELECT

FROM

60

- ASC: tng (mc nh)- DESC: gim

FROM

WHERE

ORDER BY

Mnh ORDER BY (tt)

V d

SELECT MA_NVIEN, SODA

FROM PHANCONG

ORDER BY MA_NVIEN DESC, SODA

61

SODA

10

30

999887777

999887777

MA_NVIEN

10

30987987987

987654321

987987987

10

20987654321

30987654321

Ni dung chi tit


- Truy vn c bn

62

- Truy vn c bn- Tp hp, so snh tp hp v truy vn lng- Hm kt hp v gom nhm- Mt s dng truy vn khc

Mt s hm thng dng

Php ton tp hp trong SQL

SQL c ci t cc php ton- Hi (UNION)- Giao (INTERSECT)- Tr (EXCEPT)

63

Kt qu tr v l tp hp- Loi b cc b trng nhau- gi li cc b trng nhau

UNION ALL INTERSECT ALL EXCEPT ALL

Php ton tp hp trong SQL (tt)

C php

SELECT FROM WHERE

UNION [ALL]

SELECT FROM WHERE

64

SELECT FROM WHERE

INTERSECT [ALL]

SELECT FROM WHERE

SELECT FROM WHERE

EXCEPT [ALL]

SELECT FROM WHERE

Php ton tp hp trong SQL (tt)

SELECT *

FROM NHANVIEN

WHERE PHG = 4 AND PHAI=Nu

UNION

SELECT *

SELECT *

FROM NHANVIEN

WHERE PHG = 4

INTERSECT

SELECT *

65

SELECT *

FROM NHANVIEN

WHERE PHG = 5 AND PHAI=Nam

SELECT *

FROM NHANVIEN

WHERE PHAI=Nam

SELECT * FROM NHANVIEN

EXCEPT

SELECT * FROM NHANVIEN

WHERE PHAI=Nam AND PHG = 4

Truy vn lng

SELECT MANV, TENNV



66

SELECT

FROM

WHERE (

SELECT

FROM

WHERE )

Cu truy vn cha (Outer query)

Cu truy vn con (Subquery)

M?nh d? WHERE c?a c?u truy v?n co b?n g?m cc thu?c tnh don, php so snh v?i h?ng s?

Truy vn lng (tt)

Cc cu lnh SELECT c th lng nhau nhiu mc Cu truy vn con thng tr v mt tp cc gi tr Cc cu truy vn con trong cng mt mnh

WHERE c kt hp bng php ni logic Mnh WHERE ca cu truy vn cha

67

Mnh WHERE ca cu truy vn cha- - So snh tp hp thng i cng vi mt s ton t

IN, NOT IN ALL ANY hoc SOME

- Kim tra s tn ti EXISTS NOT EXISTS

Truy vn lng (tt)

C 2 loi truy vn lng- Lng phn cp

Mnh WHERE ca truy vn con khng tham chiu nthuc tnh ca cc quan h trong mnh FROM truy vncha

Khi thc hin, cu truy vn con s c thc hin trc

68

Khi thc hin, cu truy vn con s c thc hin trc

- Lng tng quan Mnh WHERE ca truy vn con tham chiu t nht mt

thuc tnh ca cc quan h trong mnh FROM truy vncha

Khi thc hin, cu truy vn con s c thc hin nhiu ln,mi ln tng ng vi mt b ca truy vn cha

V d - Lng phn cp

SELECT MANV, TENNV

FROM NHANVIEN, DIADIEM_PHG

WHERE DIADIEM=TP HCM AND PHG=MAPHG

69

SELECT MANV, TENNV

FROM NHANVIEN

WHERE PHG IN (

SELECT MAPHG

FROM DIADIEM_PHG

WHERE DIADIEM=TP HCM )

(1, 5)

V d - Lng tng quan

SELECT MANV, TENNV



70

SELECT MANV, TENNV

FROM NHANVIEN

WHERE EXISTS (

SELECT *

FROM PHONGBAN

WHERE TENPHG=Nghien cuu AND PHG=MAPHG )

Nhn xt IN v EXISTS

IN- IN - Thuc tnh mnh SELECT ca truy vn con phi c

cng kiu d liu vi thuc tnh mnh WHERE catruy vn cha

EXISTS

71

EXISTS- Khng cn c thuc tnh, hng s hay biu thc no

khc ng trc- Khng nht thit lit k tn thuc tnh mnh

SELECT ca truy vn con- Nhng cu truy vn c = ANY hay IN u c th chuyn

thnh cu truy vn c EXISTS

Ni dung chi tit


- Truy vn c bn

72


Mt s hm thng dng

Hm kt hp

COUNT- COUNT(*) m s dng- COUNT() m s gi tr khc NULL ca

thuc tnh- COUNT(DISTINCT ) m s gi tr khc

nhau v khc NULL ca thuc tnh

73

nhau v khc NULL ca thuc tnh MIN MAX SUM AVG

Cc hm kt hp c t mnh SELECT

V d

Cho bit s lng nhn vin ca tng phng ban

SL_NV

5

4

3

3

PHG

1 1

74




333445555

987987987

MANV MA_NQL

888665555

333445555

TENLOT

Thanh

Manh

TamTran 07/31/1972 543 MTL Q1 Nu 25000 5

HangBui 07/19/1968 33 NTH Q1 Nu 38000 4

453453453

999887777

333445555

987654321

Thanh

Ngoc


QuangTran 04/08/1969 980 LHP Q5 Nam 25000 4

VinhPham 11/10/1945 450 TV HN Nam 55000 1

987987987

888665555

987654321

NULL

Hong

Van

Gom nhm

C php

SELECT

FROM

WHERE

GROUP BY

75

Sau khi gom nhm- Mi nhm cc b s c cng gi tr ti cc thuc tnh

gom nhm

GROUP BY

V d

Vi mi nhn vin cho bit m s, h tn, s lng n v tng thi gian m h tham gia

SODA THOIGIAN

1 32.5

2 7.5

123456789

123456789

MA_NVIEN

2 10.0333445555

76

2 10.0

3 10.0

333445555

333445555

10 10.0333445555

20 20.0

10 35.0

888665555

987987987

30 5.0987987987

30 20.0987654321

20 15.0987654321

1 20.0453453453

2 20.0453453453

V d

Cho bit nhng nhn vin tham gia t 2 n trln

SODA THOIGIAN

1 32.5

2 7.5

123456789

123456789

MA_NVIEN

2 10.0333445555

77

3 10.0333445555

10 10.0333445555

20 20.0

10 35.0

888665555

987987987

30 5.0987987987

30 20.0987654321

20 15.0987654321

1 20.0453453453

2 20.0453453453

b loi ra

iu kin trn nhm

C php

SELECT

FROM

WHERE

GROUP BY

78

GROUP BY

HAVING

Nhn xt

Mnh GROUP BY- Cc thuc tnh trong mnh SELECT (tr nhng thuc

tnh trong cc hm kt hp) phi xut hin trong mnh GROUP BY

Mnh HAVING- S dng cc hm kt hp trong mnh SELECT

79

- S dng cc hm kt hp trong mnh SELECT kim tra mt s iu kin no

- Ch kim tra iu kin trn nhm, khng l iu kin lctrn tng b

- Sau khi gom nhm iu kin trn nhm mi c thchin

Nhn xt (tt)

Th t thc hin cu truy vn c mnh GROUPBY v HAVING- (1) Chn ra nhng dng tha iu kin trong mnh

WHERE- (2) Nhng dng ny s c gom thnh nhiu nhm

tng ng vi mnh GROUP BY

80

tng ng vi mnh GROUP BY- (3) p dng cc hm kt hp cho mi nhm- (4) B qua nhng nhm khng tha iu kin trong

mnh HAVING- (5) Rt trch cc gi tr ca cc ct v hm kt hp trong

mnh SELECT

Ni dung chi tit


- Truy vn c bn

81


Mt s hm thng dng

Mt s dng truy vn khc

Truy vn con mnh FROM

iu kin kt mnh FROM- Php kt t nhin- Php kt ngoI

82

- Php kt ngoI

Cu trc CASE

SELECT INTO

Truy vn con mnh FROM

Kt qu tr v ca mt cu truy vn ph l mt bng- Bng trung gian trong qu trnh truy vn- Khng c lu tr tht s

C php SELECT FROM R1, R2, () AS tn_bng

83

V d

FROM R1, R2, () AS tn_bng

WHERE

SELECT MANV, TENNV

FROM NHANVIEN, (SELECT MAPHG

FROM PHONGBAN

WHERE TENPHG= Nghien cuu) AS B

WHERE PHG = MAPHG

iu kin kt mnh FROM

Kt bng

SELECT

FROM R1 [INNER] JOIN R2 ON

WHERE

84

V d

SELECT MANV, TENNV

FROM NHANVIEN INNER JOIN PHONGBAN ON PHG = MAPHG

WHERE TENPHG= Nghien cuu

iu kin kt mnh FROM

Kt ngoi

SELECT

FROM R1 LEFT|RIGHT|FULL JOIN R2 ON

WHERE

85

V d

SELECT MANV, TENNV

FROM NHANVIEN LEFT JOIN PHONGBAN ON PHG = MAPHG

Cu trc CASE

Cho php kim tra iu kin v xut thng tin theotng trng hp

C php

CASE

86

CASE

WHEN THEN

WHEN THEN

[ELSE ]

END

Cu trc CASE (tt)

SELECT MANV, TENNV , PHONG=

CASE PHG

WHEN 1 THEN N'MT'

WHEN 2 THEN N'HAI'

87

WHEN 2 THEN N'HAI'

WHEN 3 THEN N'BA'

WHEN 4 THEN N'BN'

WHEN 5 THEN N'NM'

END

FROM NHANVIEN

Select into

Dng to ra mt bng mi v a d liu vobng mi

SELECT

[INTO ]

FROM

[WHERE ]

88

V d: to bng gm nhng nhn vin nam

[WHERE ]

SELECT *

INTO NHANVIEN_NAM

FROM NHANVIEN

WHERE PHAI=NAM

Kt lun

SELECT

[INTO ]

FROM

[WHERE ]

[GROUP BY ]

89

[GROUP BY ]

[HAVING ]

[ORDER BY ]

Ni dung chi tit

Gii thiu nh ngha d liu

- Kiu d liu- Cc lnh nh ngha d liu

Truy vn d liu Cp nht d liu

90

Cp nht d liu Mt s hm thng dng

- Hm ton hc- Hm chui- Hm ngy thng- Hm chuyn i kiu

Hm ton hc

Hm Din gii V d Kt qu

Power(X,Y) Tnh X ly tha Y Select Power(2,5) 32

Round(X,n) Lm trn X cn n s l Round(123.4567,2) 123.46

Square(X) Tnh bnh phng ca X Square(5) 25

SQRT(X) Tnh cn bc 2 ca X SQRT(16)

91

SQRT(X) Tnh cn bc 2 ca X SQRT(16) 4

Sum(ct) Tnh tng ct Sum(luong)

Count(ct) m s phn t khc Null Count(MANV)

Count(*) m s dng Count(*)

Max(ct) Cho gi tr ln nht Max(luong)

Min(ct) Cho gi tr nh nht Min(luong)

Avg(ct) Tnh trung bnh ct Avg(luong)

Hm chui


Ascii(C) Tr v m Ascii ca k t C select ASCII(A) 65

Char(N) Tr v k t c m Ascii l N Char(66) B

Len(S) Tr v chiu di S Len(abc xyz) 7

92

Lower(S) Chuyn S sang ch thng Lower(abcXYZ) abcxyz

Upper(S) Chuyn S sang ch hoa Upper(abcXYZ) ABCXYZ

LTrim(S) Ct khong trng bn tri LTrim( abc) abc

Rtrim(S) Ct khong trng bn phi RTrim(abc ) abc

Left(S,n) Trch n k t bn tri S Left(abcxyz,4) abcx

Right(S,n) Trch n k t bn phi S Right(abcxyz,4) cxyz

Hm chui (tt)


S1+S2 Ni S1 vi S2 Select abc+XYZ abcXYZ

CharIndex(S1,S)

Tr v v tr u tin ca S1xut hin trong S

CharIndex(bc,abcxyzabc)

2

SubString Trch n k t t v tr p ca S SubString

93

SubString(S,p,n)

Trch n k t t v tr p ca S SubString(abcxyz,2,4)

bcxy

Replace(S1,S2,S3)

Thay tt c S2 trong S1 bng S3

Replace(ababc,ab,xy)

xyxyc

Reverse(S) Tr v chui o ngc S Reverse(abcxyz) zyxcba

Hm ngy thng

Cc hm c s dng tham s DatePart, gi tr ca DatePart c cho nh bng sau

DatePart Gi tr Din gii

DD 1-31 Ngy trong thng

94

MM 1-12 Thng trong nm

QQ 1-4 Qu trong nm

DW 1-7 (Sun-Sat) Th trong tun

YY 1753-9999 Nm

Hm ngy thng (tt)Hm Din gii V d Kt qu

GetDate() Tr v ngy gi hin hnh

Select GetDate() 2007-06-18 08:34:44.107

Day(date) Trch phn ngy Day(GetDate()) 18

Month(date) Trch phn thng Month(Getdate()) 6

Year(date) Trch phn nm Year(GetDate()) 2007

95

Year(date) Trch phn nm Year(GetDate()) 2007

DatePart(DatePart,date)

Trch DatePart ca date

DatePart(mm,GetDate())

6

DateAdd(DatePart, n,date)

Thm n DatePart vo date

DateAdd (dd,-2,Getdate())

2007-06-16

DateDiff(DatePart,date1,date2)

Tr v s DatePart gia 2 ngy

DateDiff(mm,

2007-02-16,Getdate())

4

Hm chuyn i kiu


Cast(exp AS data_type)

Chuyn gi tr exp sang kiu data_type

Cast(123 AS Int) Cast(123 AS Varchar(10))

123123

Convert(data_type,exp [,style])

Chuyn gi tr exp sang kiu

Convert(Varchar(20),GetDate(),103)

18/06/2007

96

exp [,style]) exp sang kiu data_type theo style

GetDate(),103)Convert(Varchar(20),GetDate(),101)

06/18/2007

Documents

Ch02-Ngon Ngu Truy Van SQL