SQL语句先前写的时候,很容易把一些特殊的用法忘记,我特此整理了一下SQL语句操作。 a7@':Rb n
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一、基础 R9z:K_d,
1、说明:创建数据库 6Lb(oY}\3
CREATE DATABASE database-name ?XIB\7}
2、说明:删除数据库 ~9 [O'
drop database dbname Ht9QINo
3、说明:备份sql server K8bKTG \
--- 创建 备份数据的 device =f/CBYNw@V
USE master 0;Oe&Y
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' JuKG#F#,
--- 开始 备份 |W#(+m
BACKUP DATABASE pubs TO testBack 6Lc{SR
4、说明:创建新表 yt@7l]I
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) cTJi8f=g
根据已有的表创建新表:
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A:create table tab_new like tab_old (使用旧表创建新表) 0Fw4}f.o
B:create table tab_new as select col1,col2... from tab_old definition only DEw>f%&4
5、说明:删除新表 tP][o494\&
drop table tabname B%^W$7
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6、说明:增加一个列 bt{b%r
Alter table tabname add column col type Ls`[7w
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 0H/)wy2ym
7、说明:添加主键: Alter table tabname add primary key(col) d@XXqCR<
说明:删除主键: Alter table tabname drop primary key(col) JyO2P
8、说明:创建索引:create [unique] index idxname on tabname(col....) )UCc!
删除索引:drop index idxname 1PB"1.wnd
注:索引是不可更改的,想更改必须删除重新建。 #soV'SFG
9、说明:创建视图:create view viewname as select statement bQ3txuha
删除视图:drop view viewname (yb$h0HN
10、说明:几个简单的基本的sql语句 l@)`Q
选择:select * from table1 where 范围 8g0VTY4$jP
插入:insert into table1(field1,field2) values(value1,value2) r@a]fTf
删除:delete from table1 where 范围 YO'aX
更新:update table1 set field1=value1 where 范围 bEKh U\@=J
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! Lc#GBaJ
排序:select * from table1 order by field1,field2 [desc] 2{Y~jYt{h
总数:select count as totalcount from table1 z?^oy.
求和:select sum(field1) as sumvalue from table1 re~T,PPM
平均:select avg(field1) as avgvalue from table1 ZfMs6`Wv
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最大:select max(field1) as maxvalue from table1 KTq+JT u
最小:select min(field1) as minvalue from table1 6Hp+?mmh
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11、说明:几个高级查询运算词 R*=88ds
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A: UNION 运算符 ;,}Dh/&E
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 Z%Fc
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B: EXCEPT 运算符 5%%e$o+
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 4`B3Kt`o
C: INTERSECT 运算符 _a#k3r
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 ,v%'2[}
注:使用运算词的几个查询结果行必须是一致的。 @y'0_Y0-B
12、说明:使用外连接 u4h0s1iI
A、left outer join: ^)y8X.iO
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 Yb=77(QV
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c 3=Q:{
B:right outer join: RH.qbPjx
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 5-hnk'
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C:full outer join: Z)}UCi+/".
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 zM,r0Z
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二、提升 D5bPF~q
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) )bWopc
法一:select * into b from a where 1<>1
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法二:select top 0 * into b from a Z]e`bfNnI
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) +Bf?3 5LP
insert into b(a, b, c) select d,e,f from b; s&hr$`V4
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) lA pZC6Iwk
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 P8(hHuO
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. ^Z-oO#)h#
4、说明:子查询(表名1:a 表名2:b) uzI=.j
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) u"uL,w
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5、说明:显示文章、提交人和最后回复时间 [!De|,u(^
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b 57~y 7/ 0
6、说明:外连接查询(表名1:a 表名2:b) Ptc+ypTu
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c -&COI-P8
7、说明:在线视图查询(表名1:a ) XEnu0gr
select * from (SELECT a,b,c FROM a) T where t.a > 1; W=#AfPi$&
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 }T0O~c{$i
select * from table1 where time between time1 and time2 PY;tu#W!%
select a,b,c, from table1 where a not between 数值1 and 数值2 Khb Ku0Z
9、说明:in 的使用方法 AhD C5ue=
select * from table1 where a [not] in ('值1','值2','值4','值6') jU $G<G
10、说明:两张关联表,删除主表中已经在副表中没有的信息 sH.=Faos
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) _jc_(;KPF
11、说明:四表联查问题: O%3Hp.|!
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... <PVwf`W.
12、说明:日程安排提前五分钟提醒 ae2Q^yLA
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 Wqkb1~]#Y
13、说明:一条sql 语句搞定数据库分页 o{6q>Jm
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 \{}dn,?Fv
14、说明:前10条记录 N+ak{3
select top 10 * form table1 where 范围 8qqN0"{,
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.)
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select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) x_/}R3d
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 n1JtY75#,/
(select a from tableA ) except (select a from tableB) except (select a from tableC) j*5IRzK1%0
17、说明:随机取出10条数据 $&=xw _
select top 10 * from tablename order by newid() 8PzGUn;\
18、说明:随机选择记录 j.ucv
select newid() pB4Uc<e
19、说明:删除重复记录 @)BO`;*$fF
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) WR3,woo
20、说明:列出数据库里所有的表名 43pe6 ^.
select name from sysobjects where type='U' |mP};&b
21、说明:列出表里的所有的 ^$50[
select name from syscolumns where id=object_id('TableName') A#6zINK#B
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 LQHL4jRXU
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type {O9(<g
显示结果: 1$8@CT^m
type vender pcs Z2gWa~dBC
电脑 A 1 {nbT$3=Zt
电脑 A 1 ;F#(:-:
光盘 B 2 F~8'3!<9
光盘 A 2 R0}1:1}$Sn
手机 B 3 K8aqC{
手机 C 3 *68 TTBq(
23、说明:初始化表table1 :{2~s
TRUNCATE TABLE table1 +i!5<nn
24、说明:选择从10到15的记录 wS);KLe3
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc CVWT>M<
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三、技巧 !(rAI
1、1=1,1=2的使用,在SQL语句组合时用的较多 #n'.a1R
"where 1=1" 是表示选择全部 "where 1=2"全部不选,
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如: `Bw]PO
if @strWhere !='' ^3TNj
begin J\r\_P@;c
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere ]bJz-6u#:
end +U2lwd!j
else "~5cz0
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begin E?G'F3i
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' J7* o%W*V
end X58U>4a
我们可以直接写成 bDM },(
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere R>*z8n
2、收缩数据库 *^uK=CH1?(
--重建索引 %(1OjfZc
DBCC REINDEX ~<?Zj
DBCC INDEXDEFRAG l[Z o,4*
--收缩数据和日志 R(d<PlZ
DBCC SHRINKDB *qwN9b/!
DBCC SHRINKFILE Qz,2PO
3、压缩数据库 _6nAxm&x`%
dbcc shrinkdatabase(dbname) u<Kowt<ci
4、转移数据库给新用户以已存在用户权限 UPI- j#yc
exec sp_change_users_login 'update_one','newname','oldname' "5&"Ij,/
go Y
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5、检查备份集 tL$,]I$1+
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' 0+e=s0s.
6、修复数据库 AP=h*1udk
ALTER DATABASE [dvbbs] SET SINGLE_USER =P]Z"Ok
GO ^Hv&{r77
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK px<psR5
GO Lw}-oE
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ALTER DATABASE [dvbbs] SET MULTI_USER =I`S7oF
GO =mO5~~"W+v
7、日志清除 hBjU(}\3
SET NOCOUNT ON 6u0>3-[6OD
DECLARE @LogicalFileName sysname, } Bf@69
@MaxMinutes INT, Jt=->
@NewSize INT `qc"JB
USE tablename -- 要操作的数据库名 [UA*We 1
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 ,*J@ic7"
@MaxMinutes = 10, -- Limit on time allowed to wrap log. s/tLY/U/
@NewSize = 1 -- 你想设定的日志文件的大小(M) >$JE!.p%o
-- Setup / initialize C< c6Ub
DECLARE @OriginalSize int y>EW,%leC
SELECT @OriginalSize = size Vr
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FROM sysfiles w$:\!FImx
WHERE name = @LogicalFileName gx.\H3y
SELECT 'Original Size of ' + db_name() + ' LOG is ' + In1W/?
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + ;OlnIxH(W
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' c!ZZMCs
FROM sysfiles J<0{3pZY
WHERE name = @LogicalFileName 9wYm(7M6
CREATE TABLE DummyTrans ~_fc=^o
(DummyColumn char (8000) not null) wa8jr5/k"
DECLARE @Counter INT, a9-Mc5^'n
@StartTime DATETIME, NPK;
@TruncLog VARCHAR(255) ga;nM#/
SELECT @StartTime = GETDATE(), Uj7YTB
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' e,JBz~CK*w
DBCC SHRINKFILE (@LogicalFileName, @NewSize) l+9RPJD/:
EXEC (@TruncLog) ZAr6RRv ^
-- Wrap the log if necessary. H~Uf2A)C
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired Sb[>R(0:
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) k24I1DlR8
AND (@OriginalSize * 8 /1024) > @NewSize V
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BEGIN -- Outer loop. .dU91> ~Ov
SELECT @Counter = 0 },8|9z#pyB
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) NftnbsTmy
BEGIN -- update "z{/*uM2<
INSERT DummyTrans VALUES ('Fill Log') Cw,a)XB
DELETE DummyTrans /x??J4r0
SELECT @Counter = @Counter + 1 yv4x.cfI2W
END \6|y~5Hw{r
EXEC (@TruncLog) 1eD#-tzV
END Mt4
SELECT 'Final Size of ' + db_name() + ' LOG is ' +
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CONVERT(VARCHAR(30),size) + ' 8K pages or ' + s9ix&m
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' rRRh-%.RU
FROM sysfiles .V
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WHERE name = @LogicalFileName .b,\.0N
DROP TABLE DummyTrans JKZVd`fF
SET NOCOUNT OFF $VmV>NZ
8、说明:更改某个表 e3ZRL91c
exec sp_changeobjectowner 'tablename','dbo' F_qApyU,7
9、存储更改全部表 3N_KNW
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch ';3>rv_
@OldOwner as NVARCHAR(128), M2Nh3ijr
@NewOwner as NVARCHAR(128) f SkC>mWv
AS PEI$1,z
DECLARE @Name as NVARCHAR(128) {N2GRF~c-y
DECLARE @Owner as NVARCHAR(128) 8xLQ"
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DECLARE @OwnerName as NVARCHAR(128) *|y'%y
DECLARE curObject CURSOR FOR ww{k_'RRJ
select 'Name' = name, FEk9a^Xyx
'Owner' = user_name(uid) Xex7Lr&
from sysobjects ^aB;Oo
where user_name(uid)=@OldOwner g$uiwqNA%
order by name S%\5"uGa
OPEN curObject +ywz@0nx
FETCH NEXT FROM curObject INTO @Name, @Owner HIc;Lc8$
WHILE(@@FETCH_STATUS=0) Z;uKnJh
BEGIN zeMV_rW~
if @Owner=@OldOwner 8'Q+%{?1t
begin XZOBK^,5^B
set @OwnerName = @OldOwner + '.' + rtrim(@Name) =78y*`L
exec sp_changeobjectowner @OwnerName, @NewOwner .4a|^ vT
end QT%`=b
-- select @name,@NewOwner,@OldOwner Z?eTjkNS#
FETCH NEXT FROM curObject INTO @Name, @Owner NOTG|\{
END ._0$#J S[
close curObject 5S4Nx>
deallocate curObject K}cZK
GO &>c=/]Lop
10、SQL SERVER中直接循环写入数据 Qr
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declare @i int %bP+P(vZ
set @i=1 &b@_ah+f
while @i<30 )zWu\JRp
begin (Mfqzy
insert into test (userid) values(@i) TIp\-
set @i=@i+1 ^6l5@#)w
end usc/DQ1
小记存储过程中经常用到的本周,本月,本年函数 Kh3i.gm7g
Dateadd(wk,datediff(wk,0,getdate()),-1) {Vu=qNx
Dateadd(wk,datediff(wk,0,getdate()),6) /uWUQ#9
Dateadd(mm,datediff(mm,0,getdate()),0) niS\0ZA
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) YMw,C:a4
Dateadd(yy,datediff(yy,0,getdate()),0) \l=A2i7TQ
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) vVB WhY]
上面的SQL代码只是一个时间段 O.dZ3!!+
Dateadd(wk,datediff(wk,0,getdate()),-1) gX!K%qJBg
Dateadd(wk,datediff(wk,0,getdate()),6) bmHj)^v5]
就是表示本周时间段. A5R"|<UPR
下面的SQL的条件部分,就是查询时间段在本周范围内的: `m'RvU c
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) mCnl@
而在存储过程中 .B^tEBGVD
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) Z%?>H iy'o
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) GNW$:=0u