Chuong#3 Truy Van Nang Cao

Chng 3

Truy vn nng cao

www.themegallery.com

Ni dung

Cu trc lnh

Th tc thng tr

Kiu d liu cursor

Hm ngi dng 4

1

2

3


Khai bo bin

Tn bin?

Tm vc bin?

Kiu d liu?

Gi tr khi to?


Khai bo bin

C php

Declare Var_name Datatype

Lu : Tn bin phi bt u bng 1 k t @

V d

Declare @MaSinhVien nvarchar(10)

Declare @TienLuong float

Declare @Sum float, @Count int

Declare @temp TABLE (ma int,

ten nvarchar(10))


Khai bo bin

Tm vc bin

Bin cc b c ngha trong mt query batch hay mt th tc thng tr hoc mt hm ngi dng

Bin h thng c ngha trn c h thng. Tn ca chng bt u bng @@. Cc bin ny l read-only.

V d bin h thng : @@fetch_status, @@rowcount, @@trancount


Lnh gn

Set @TenBien = GiaTri

Set @TenBien = TenBien

Set @TenBien = BieuThuc

Select @TenBien = (KetQuaTruyVan)

V d :

Set @MaLop = TH2001

Set @SoSV = (select count(*) from SinhVien)

Set @MaLop = TH + CAST (Year(@NgayTuyenSinh) AS char(4))


Lnh gn

Cng c th gn gi tr cho bin bng cu truy vn thay v ch th set

V d :

SV(MaSV, HoTen, Tuoi)

Select @Var2 = HoTen, @Var1 = Tuoi

from SV

where MaSV = 1

Kiu d liu phi tng ng. Nu cu truy vn tr v nhiu dng th cc bin ch nhn gi tr t dng u tin


Cu trc iu khin

If

[Begin]

Code block

[End]

Else

[Begin]

Code block

[End]

C Php

C th cha cc cu truy vn phc tp ty

Khai bo bin Cc tnh ton trn bin Cc cu truy vn phc tp ty

Optional


Cu trc iu khin If logial expression

[Begin]

Code block

[End]

[Else if logial expression

[Begin]

Code block

[End]

[,n]] Else

[Begin]

Code block

[End]

C th lp li nhiu ln ty . M phng cu trc case


Cu trc iu khin V d

HocPhan(MaHP, TenHP, SiSo)

DangKy(MaSV, MaHP)

Vit lnh thm mt ng k mi cho sinh vin c m s 001 vo hc phn HP01 (gi s hc phn ny tn ti trong bng HocPhan). Qui nh s s lp cho mi hc phn khng qu 50 sv


Cu trc iu khin

WHILE

[Begin]

{ sql_statement | statement_block }

[ BREAK ]

{ sql_statement | statement_block }

[ CONTINUE ]

[End]

Thot vng lp

B qua on lnh sau


Cu trc iu khin V d

SinhVien(MaSV: int, HoTen: nvarchar(30))

Vit lnh xc nh mt m sinh vin mi theo qui nh: m sinh vin tng dn, nu c ch trng th m mi xc nh s chn vo ch trng

Vd: 1,2,3,7 m sinh vin mi: 4


Cu trc iu khin

CASE [input_expression]

WHEN when_expression THEN result_expression

[ ...n ]

[ ELSE else_result_expression ]

END

C th l gi tr hoc biu thc iu kin


Cu trc iu khin

V d:

NHAN_VIEN(MaNV, HoTen, NgaySinh, CapBac,

Phai)

Cho bit nhng nhn vin n tui v hu (tui v hu ca nam l 60, ca n l 55)


Cu trc iu khin

Select * From NHAN_VIEN

Where datediff(yy, NgaySinh, getdate())

> = Case Phai

when Nam then 60

when Nu then 55

End


Cu trc iu khin

Cho bit m NV, h tn v loi nhn vin (cp bc


Bi tp 1

Cho 3 s a, b, c.

Tm phn s nh nht. In gi tr ca a, b, c.

Xut thng bo "S nh nht l :"


Bi tp 1

1. Declare @a int, @b float, @c int

2. Set a = 2

3. Select b = 2.4

4. set c = 2.5

5. print 'a=' + @a + 'b=' + @b + ' c=' + @c

6. If @a>@b

7. select @tmp = @b

8. if @b>@c

9. set @tmp = @c

10. if @c>@a

11. set @tmp = @a

12. print 'S nh nht l: ' + @tmp

Tm li


Bi tp 2

Cho CSDL:

SinhVien (MaSV, Hoten, DiemTB)

Tm sinh vin c im trung bnh ln nht v xut thng

bo theo yu cu sau:

Nu im TB >= 8.0 [MaSV] - im trung bnh [DiemTB] Xp loi : Gii

Nu im TB >= 6.5 [MaSV] - im trung bnh [DiemTB] Xp loi : Kh

Nu im TB >= 5.0 [MaSV] - im trung bnh [DiemTB] Xp loi : Trung bnh

Ngc li [MaSV] - im trung bnh [DiemTB] Xp loi : Yu


Bi tp 3

Cho CSDL:

SinhVien(MaSV, HoTen, NgaySinh)

Tm sinh vin c MaSV = 0912033 vi nh

dng nh sau:

------------------------------------

M SV : 0912033

H tn : Nguyn Kim i

Ngy sinh : 20/9/1990

-------------------------------------


Bi tp 4

Cho CSDL:


DiemThi(MaSV, MaMH, Diem)

Tnh im trung bnh ca tng sinh vin. Nu sinh

vin c im trung bnh > 5.0 th in l u ngc

li rt. In di dng bng.

V d:

MaSV HoTen im TB Kt qu

0912033 Nguyn Kim i 4.5 Rt


Bi tp 5

Cho CSDL:


DiemThi(MaSV, MaMH, Diem)

Kim tra MaSV = 0912003 c tn ti cha

Nu cha tn ti xut thng bo [MaSV] cha tn ti.

Ngc li, xut thng bo [MaSV] sinh vin tn ti.


Bi tp 6

Cho CSDL:

MonHoc(MaMH, TenMH,SoChi)

Kim tra MaMH tn ti cha?

Nu tn ti ri xut thng bo [MaMH] tn ti

Ngc li, pht sinh MaMH mi v in thng bo M MH mi l [MaMHmoi]

V d:

Tm c MaMH ln nht l : MH008

Pht sinh MaMH mi = MH009


Ni dung

Cu trc lnh

Th tc thng tr

Kiu d liu cursor

Hm ngi dng 4

1

2

3


Th tc thng tr

Th tc: Cha cc lnh T_SQL Tng t nh mt th tc trong cc ngn ng lp trnh: c th truyn tham s, c tnh ti s dng

Thng tr: c dch v lu tr thnh mt i tng trong CSDL


Th tc thng tr

Tn th tc?

Gi tr tr v?

Tham s ra?

Yu cu x l?

Tham s vo?


ngha

Tnh ti s dng

Ti u ha khi bin dch

Gim lng thng tin trao i

m bo an CSDL an ton hn

n gin ha vic lp bo co


C php

Create {proc | procedure} proc_name

Parameter DataType [output] [,n]

As

Code block

[return [return_value] ]

Go

Tn ca stored .Nn bt u vi USP

Tn tham s (t nh tn bin)

Kiu DL ca tham s Gi tr tr ra nu c

th dng mt (hay mt s) tham s output

Thn sa SP, vit nh th no l ty vo tng bi ton c th

Ch tr v gi tr int


V d

Vit th tc thm mt ng k ca sinh vin vo mt hc phn

--1. Khai bo i s

Create procedure usp_ThemDangKy

@MaSV char(5),

@MaHP char(5),

@SiSo int = null output

As


V d --2. Khai bo ni dung

Declare @SiSo int

Select @SiSo = SiSo From HocPhan Where MaHP= @MaHP

if @SiSo < 50

Begin

insert into DANG_KY(MaSV, MaHP)

values(@MaSV, @MaHP)

set @SiSo = @SiSo+1

return 1

End

return 0

Go

Tn tham s (t nh tn bin)


Stored-Procedure

Kim tra

tn ti?

Stored-

procedure

Phn tch

c php

Bo li!

Kim tra

tn ti?

Thnh

cng!

Thnh

cng!

Bin dch

khi thc thi


Scalar input parameters

CREATE PROC USP_XemSV

@MaSV Char(10)

AS

BEGIN

IF @MaSV is NULL

SELECT * FROM SINHVIEN

ELSE

SELECT *

FROM SINHVIEN

WHERE MaSV = @MaSV

END

EXEC USP_XemSV 0912311


Table-valued input parameters

--Khai bo kiu d liu mi

CREATE TYPE DSCTDonHang AS TABLE

(

MaSP char(10) UNIQUE,

DonGia float,

SoLuong int

)

--Thm d liu vo bng @temp

DECLARE @temp DSCTDonHang

INSERT @temp VALUES('1','1',3)

SELECT * FROM @temp



CREATE PROC USP_THEMHOADON

@TEMP AS DSCTDONHANG READONLY,

@MADONHANG CHAR(10),

@MAKHACHHANG CHAR(10)

AS

BEGIN

--Thm phiu t hng

INSERT PHIEUDATHANG (MADATHANG,NGAYDAT,MAKHACHHANG)

VALUES(@MADONHANG, GETDATE(), @MAKHACHHANG)

--Thm chi tit phiu t hng

INSERT CHITIETPHIEUDAT (MACHITIETPD,MASANPHAM,SOLUONG,MADATHANG)

SELECT *, @MADONHANG FROM @TEMP

END



--Khai bo danh sch chi tit n hng

DECLARE @TEMP DSCTDONHANG

--Thm chi tit vo danh sch

INSERT @TEMP

VALUES('CT00000009','SP00000005',2),

('CT00000010','SP00000003',2)

--Xem ni dung bng @temp

SELECT * FROM @TEMP

--Thc thi th tc

EXEC USP_THEMHOADON @TEMP,'DH001','KH00000001'


Scalar output parameters

Thng k doanh thu ca mi sn phm

CREATE PROC USP_ThongKe

@MaSP Char(10),

@TongSLBan int output,

@TongDoanhThu float output

AS



BEGIN

--Tnh tng s lng

SET @TongSLBan = (SELECT SUM(SoLuong)

FROM CHITIETPHIEUDAT

WHERE MaSanPham = @MaSP)

--Tnh tng doanh thu

SET @TongDoanhThu =

(SELECT SUM(SoLuong * DonGia)

FROM CHITIETPHIEUDAT

WHERE MaSanPham = @MaSP)

END



--Gi thc thi

DECLARE @TongSL int, @TongDT float

EXEC USP_ThongKe 'SP00000001',

@TongSL output,

@TongDT output

PRINT CAST(@TongSL AS Char(3)) + Char(13)

PRINT @TongDT


Gi thc thi

{EXEC| EXECUTE}

[ @return_status = ] procedure_name

{ [ @parameter _name = ] value [ OUTPUT ] } [ ,...n ]

@parameter_name dng khi tham s l output

Value c th l gi tr hoc bin, v phi truyn ng th t khai bo


V d --1. Truyn tr

Exec usp_ThemDangKy 001, HP01

--2. Truyn tr c tn bin

Exec usp_ThemDangKy @MaHP = HP01, @MaSV = 001

--3. Truyn tr c tn bin

Exec usp_ThemDangKy @MaHP, @MaSV

--4. C output

Declare @SiSo int

Exec usp_ThemDangKy 001,HP01, @SiSo output

--5. Nhn li gi tr t hm

Declare @SiSo int, @KetQua int

Exec @KetQua = usp_ThemDangKy 001,HP01, @SiSo output


Th tc thng tr

Sa th tc

Thay t kha Create trong lnh to th tc bng t kha Alter

Xa th tc

Drop {procedure|proc} procedure_name

V d:

Drop procedure usp_ThemDangKy


Th tc thng tr

Th mc cha th tc


Th tc lng nhau

Create proc A

AS

Begin

-- Cc lnh

End

Create proc B

AS

Begin

EXEC A

-- Cc lnh

End


Bi tp

CSDL:

SinhVien (MaSV, HoTen, MaLop)

Lop(MaLop, Siso)

KetQua(MaSV, MaMH, Diem)

1. Vit th tc nhp vo MaSV kim tra sinh vin c

tn ti.

2. Vit th tc thm 1 SV vo CSDL. Cp nht s s

lp (Nu s sv > 50. Thng bo lp y.)


Ni dung

Cu trc lnh

Th tc thng tr

Kiu d liu cursor

Hm ngi dng 4

1

2

3


Cursor Khi nim

MaSV Hoten NgaySinh

SV001 Nguyn Minh Thu 20/1/1990

SV002 Nguyn Th Thch 2/3/1991

SV003 Trn Minh Trang 4/3/1990

tempCol MaSV Hoten NgaySinh

1 SV001 Nguyn Minh Thu 20/1/1990

2 SV002 Nguyn Th Thch 2/3/1991

3 SV003 Trn Minh Trang 4/3/1990

WHILE CURSOR


Cursor Khi nim

L mt cu trc d liu nh x n mt tp cc dng d liu l kt qu ca mt cu truy vn (select)

Cho php duyt tun t qua tp cc dng d liu v c gi tr tng dng.


Cursor khi nim

V tr hin hnh ca cursor c th c dng nh iu kin trong mnh where ca lnh update hoc delete

Cho php cp nht / xo d liu (d liu tht s trong CSDL) tng ng vi v tr hin hnh ca cursor


Cursor khai bo

C th khai bo theo c php chun hoc c php m rng ca T-SQL

C php chun Declare cur_name [Insensitive] [Scroll] Cursor

For select_statement

[ For {Read only| Update [of column_name [,n] ] } ]


Cursor Khai bo

C php m rng Declare cursor_name Cursor

[ Local | Global ]

[ Forward_only| Scroll]

[ Static| Dynamic]

[ Read_only]

For select_statement

[ For Update [ of column_name [,n] ] ]


Cursor Khai bo

Cursor_name:

Chiu di 128 k t

C 2 cch khai bo Tn cursor Tn tnh m t cho mt i tng

cursor. Tn cursor s c gn bng i tng cursor thng qua cu lnh Declare.

VD:

DECLARE cur CURSOR

FOR SELECT MSSV, TenSV FROM SINHVIEN


Cursor Khai bo

Bin cursor cursor c khai bo nh mt bin kiu CURSOR, khi gn gi tr cho bin cursor thng qua lnh SET th bin ny s tr ti i tng cursor.

VD:

DECLARE @cur CURSOR

SET @cur = CURSOR

FOR SELECT MSSV, TenSV FROM SINHVIEN

HOC

DECLARE @cur CURSOR

SET @cur = my_cur


Cursor Khai bo

ngha cc tham s ty chn:

Insensitive / static: ni dung ca cursor khng thay i trong sut thi gian tn ti, trong trng hp ny cursor ch l read only.

Dynamic: trong thi gian tn ti, ni dung ca cursor c th thay i nu d liu trong cc bng lin quan c thay i.


Cursor Khai bo

Local: cursor cc b, ch c th s dng trong phm vi mt khi (query batch) hoc mt th tc/ hm

Global: cursor ton cc (tn ti trong sut connection hoc n khi b hy tng minh)


Cursor Khai bo

Forward_only: cursor ch c th duyt mt chiu t u n cui

Scroll: c th duyt ln xung cursor ty

Read only: ch c th c t cursor, khng th s dng cursor update d liu trong cc bng lin quan (ngc li vi for update )


Cursor Khai bo

Mc nh:

Global

Forward_only

For update

Dynamic


Cursor Khai bo

Bng tng thch

Insensitive Scroll Read Only Update

Insensitive

Scroll

Read Only

Update


Cursor Khai bo

Local Global Static Dynamic Read_only Update Forward_only Scroll

Local

Global

Static

Dynamic

Read_only

Update

Forward_only

Scroll


Cursor - Duyt cursor

Mc nh : fetch next

i vi cursor dng forward_only, ch c th fetch next

Bin h thng @@fetch_status cho bit lnh fetch va thc hin c thnh cng hay khng


@@fetch_status

Trc lnh fetch u tin: @@fetch_status khng xc nh

Fetch next ln u tin: @@fetch_status =0 (thnh cng)

@@ fetch_status 0

Object


Trnh t s dng Khai bo cursor

M cursor bng lnh Open

Open tn_cursor

Fetch (next,) cursor chuyn n v tr ph hp

Dng lnh INTO a gi tr ca cursor vo bin

Nu khng c lnh INTO, gi tr ca cursor s hin th ra mn hnh kt qu sau lnh fetch

C th s dng v tr hin ti nh l iu kin cho mnh where ca cu delete/ update (nu cursor khng l read_only)


Trnh t s dng

Lp li vic duyt v s dng cursor, c th s dng bin @@fetch_status bit duyt qua ht cursor hay cha.

ng cursor bng lnh Close Close Tn_cursor

Hy cursor bng lnh deallocate Deallocate Tn_cursor

Sau khi ng, vn c th m li nu cursor cha b hy


V d 1 --1. Khai bo

Declare cur_DSKhoa Cursor

For Select MaKhoa, TenKhoa From Khoa

--2. M cursor

Open cur_DSKhoa

Declare @MaKhoa int, @TenKhoa varchar(30)

--3. Np cursor ln 1

Fetch Next From cur_DSKhoa into @MaKhoa,

@TenKhoa


--4. Fetch ln 2n

While @@fetch_status = 0

Begin

update SinhVien

set MaSV = MaKhoa +MaSV

Where MaKhoa = @MaKhoa

Fetch Next From cur_DSKhoa into @MaKhoa,

@TenKhoa

End


--5. ng cursor

Close cur_DSKhoa

--6. Hy cursor

Deallocate cur_DSKhoa


V d 2 Dng cursor cp nht dng xc nh

Declare cur_DSKhoa cursor scroll For

select MaKhoa, TenKhoa

From Khoa

Open cur_DSKhoa

Fetch Absolute 2 From cur_DSKhoa

If (@@fetch_status = 0)

Update Khoa

Set TenKhoa = aaa

Where current of cur_DSKhoa

Close cur_DSKhoa

Deallocate cur_DSKhoa


Ni dung

Cu trc lnh

Kiu d liu cursor

Th tc thng tr

Hm ngi dng 4

1

2

3


Hm ngi dng

Ging stored procedure:

L m lnh c th ti s dng

Chp nhn cc tham s input

Dch mt ln v t c th gi khi cn

Khc stored procedure

Chp nhn nhiu kiu gi tr tr v (ch mt gi tr tr v)

Khng chp nhn tham s output

Khc v cch gi thc hin


Hm ngi dng

Phn loi : gm 3 loi

Gi tr tr v l kiu d liu c s (int, varchar, float, datetime) th mc Scalar value function

Gi tr tr v l Table c c t mt cu truy vn th mc Table value function

Gi tr tr v l table m d liu c c nh tch ly dn sau mt chui thao tc x l v insert. th mc Table value function


Hm ngi dng

Loi 1: Gi tr tr v l kiu d liu c s

Create function func_name

( {parameter_name DataType [= default ] }

[,n])

Returns DataType

As

Begin

Return {value | variable | expression}

End

D khng c tham s cng phi ghi cp ngoc rng

D thn function ch c 1 lnh cng phi t gia Begin v End


V d

Tm s ln nht trong 3 s a, b, c Create function UF_SoLonNhat (@a int,@b int,@c int)

Returns int

As

Begin

Declare @max int

Set @max = @a

If @b > max set @max = @b

If @c > max set @max = @c

Return @max

End


Hm ngi dng

Loi 2: Gi tr tr v l Table c c t mt cu truy vn


( {parameter_name DataType [= default ] }

[,n])

Returns Table

As

Return [ ( ]select_statement [ ) ]

Go

Thn function lun

ch c mt lnh,

khng t trong cp

Begin -End


Hm ngi dng

Loi 3: Gi tr tr v l table m d liu c c nh tch ly dn sau mt chui thao tc x l v insert.


( {parameter_name DataType [= default ] } [,n])

Returns TempTab_name Table(Table_definition)

As

Begin

Return

End


V d Create function uf_DanhSachLop

Returns @DS

Table(MaLop varchar(10),SoSV int)

As

Declare cur_L cursor for Select Ma From Lop

Declare @Ma varchar(10)

Open cur_L

Fetch next from cur_L into @Ma

While @@fetch_status=0

Begin

. End

Close cur_L

Deallcocate cur_L

Return

Go

Insert into @DS

Values (@Ma, (select count(*) from

SinhVien where Lop=@Ma))

Fetch next from cur_L into @Ma


S dng hm

Cc hm ngi dng c s dng trong cu truy vn, trong biu thc ph hp kiu d liu tr v ca n

V d:

Select dbo.SoLonNhat(3,5,7)

Select * from DanhSachLop()


Hm ngi dng

Lu : khi gi hm loi 1 (tr v gi tr c bn), phi c tn owner ca hm i km

V d dbo.uf_SoLonNhat()


Hm ngi dng

Thay i hm ngi dng

Thay t kha create trong cc lnh to hm bng t kha alter

Xa hm ngi dng

Drop Function Tn_Hm_Cn_Xa

V d :

Drop Function uf_DanhSachMatHang


Hm ngi dng

Ngoi cc hm do ngi dng nh ngha, SQL Server cn cung cp cc hm xy dng sn ca h thng

Cc hm ny cung cp tin ch nh x l chui, x l thi gian, x l s hc

Sinh vin tm hiu thm v cc hm ny trong Books on-line v cc ti liu tham kho


Hm ngi dng

Th mc cha hm ngi dng

Th mc cha hm h thng

Loi 1

Loi 2, 3


Bi tp

SinhVien (MaSV, HoTen, MaLop)

Lop(MaLop, Siso)

KetQua(MaSV, MaMH, Diem)

1. Vit hm tnh im trung bnh ca sinh vin.

2. Vit hm tm m sinh vin c im trung bnh cao

nht.

3. Vit hm xut danh sch cc sinh vin c im < 5.

4. Vit th tc xp loi cho sinh vin (gi hm cu 1).

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Chuong#3 Truy Van Nang Cao