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。 7tpAZ<{
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一、基础 3]O`[P,*%
1、说明:创建数据库 ,wtFs!8
CREATE DATABASE database-name n-b>m7O(
2、说明:删除数据库 J)9 AnGWe
drop database dbname 5h`m]#YEG
3、说明:备份sql server K&=1Ap
--- 创建 备份数据的 device *Q bM*oH
USE master :/o C:z\h
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' `Y\gSUhzS
--- 开始 备份 i\t753<Ys
BACKUP DATABASE pubs TO testBack ; cGv] A+
4、说明:创建新表 o3Mf:;2c C
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) B#FHf
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根据已有的表创建新表: W|)GV0YM
A:create table tab_new like tab_old (使用旧表创建新表) \hs/D+MCk
B:create table tab_new as select col1,col2... from tab_old definition only 9@:BK;Fi
5、说明:删除新表 iuiAK
drop table tabname y,MPGW_
6、说明:增加一个列 uQH%.A
Alter table tabname add column col type \Dn&"YG7
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。 GwcI0~5
7、说明:添加主键: Alter table tabname add primary key(col) LtC~)R
说明:删除主键: Alter table tabname drop primary key(col) ;tJWOm
8、说明:创建索引:create [unique] index idxname on tabname(col....) CPVzX%=
删除索引:drop index idxname C">`' G2
注:索引是不可更改的,想更改必须删除重新建。 V?OuIg%=:
9、说明:创建视图:create view viewname as select statement
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删除视图:drop view viewname !n|#|.0m
10、说明:几个简单的基本的sql语句 + c`AE
选择:select * from table1 where 范围 7$!yfMttu
插入:insert into table1(field1,field2) values(value1,value2) 9lKn%|=T
删除:delete from table1 where 范围 OkLz^R?d
更新:update table1 set field1=value1 where 范围 n'THe|:I
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! yH*hL0mO
排序:select * from table1 order by field1,field2 [desc] xpF](>LC(
总数:select count as totalcount from table1 $30oc
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求和:select sum(field1) as sumvalue from table1 v2d<o[[C
平均:select avg(field1) as avgvalue from table1 9X( Sk%
最大:select max(field1) as maxvalue from table1 (B@X[~
最小:select min(field1) as minvalue from table1 grr'd+_ e
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11、说明:几个高级查询运算词 X2qv^G,
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A: UNION 运算符 S.{fDcM
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。 NetYg]8`
B: EXCEPT 运算符 vYdR ht\(
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。 (?vK_{
C: INTERSECT 运算符 BWh}^3?l
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。 joqWh!kv7U
注:使用运算词的几个查询结果行必须是一致的。 /be=u@KV
12、说明:使用外连接 []zua14F6
A、left outer join: Y6A;AmM8
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。 &f-hG3/M
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 :$?Q D
B:right outer join: yYY Nu`
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 \6o\+OQk
C:full outer join: LEZ&W;bCo
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 /4*W DiH
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二、提升 ?DPHo)w
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) <J&7]6Z
法一:select * into b from a where 1<>1 'Dath>Y=
法二:select top 0 * into b from a M(enRs3`O
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) )u*^@Wo
insert into b(a, b, c) select d,e,f from b; z\T Lsx
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) &$=! dA
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 ?'eq",c#4N
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. "UG
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4、说明:子查询(表名1:a 表名2:b) xzm@
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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) _okWQvdH
5、说明:显示文章、提交人和最后回复时间 n-J2/j
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b &w85[zs
6、说明:外连接查询(表名1:a 表名2:b) irKIy
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c FJ54S
7、说明:在线视图查询(表名1:a ) O)]v;9oER
select * from (SELECT a,b,c FROM a) T where t.a > 1; ^:KO_{3E
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 G-u]L7t&1
select * from table1 where time between time1 and time2 NmpnJu|8
select a,b,c, from table1 where a not between 数值1 and 数值2 632bN=>
9、说明:in 的使用方法 pK}=*y~$
select * from table1 where a [not] in ('值1','值2','值4','值6') `s"d]/85VW
10、说明:两张关联表,删除主表中已经在副表中没有的信息 n?xTkkr0
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) s^hR\iY
11、说明:四表联查问题: iPj~I
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 ..... e,gyQjJR
12、说明:日程安排提前五分钟提醒 !L$x:/R9M
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 -SCM:j%h
13、说明:一条sql 语句搞定数据库分页 28I^$> [
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 h4)Bs\==mT
14、说明:前10条记录 w0lT%CPx
select top 10 * form table1 where 范围 wTc)S6%7
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.) 56}X/u
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) FX}Gt=
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 swcd&~9r
(select a from tableA ) except (select a from tableB) except (select a from tableC) ;9a 6pz<
17、说明:随机取出10条数据 ztll}
select top 10 * from tablename order by newid() W7sn+g\
18、说明:随机选择记录 `A@w7J'
select newid() "i^
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19、说明:删除重复记录 EGVM)ur
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) zM#sOg
20、说明:列出数据库里所有的表名 78 f$6J q
select name from sysobjects where type='U' !l@zT}i??
21、说明:列出表里的所有的 ==N{1gO]
select name from syscolumns where id=object_id('TableName') nz]&a1"&
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 M@et6aud;K
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type #xh_
显示结果: S\i@s_
type vender pcs I\O\,yPhhP
电脑 A 1 88s/Q0l
电脑 A 1 dT"hNHaf
光盘 B 2 ;&b.T}Nf06
光盘 A 2 V)ig)(CT
手机 B 3 GL$De,V
手机 C 3 saf&dd
23、说明:初始化表table1 q*7<)VwI
TRUNCATE TABLE table1 "R>FqX6FB
24、说明:选择从10到15的记录 n2B){~vE
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc NoE*/!Sr
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三、技巧 W !w, f;
1、1=1,1=2的使用,在SQL语句组合时用的较多 b;sVls
"where 1=1" 是表示选择全部 "where 1=2"全部不选, Z<[<n0o1
如: +ZMls
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if @strWhere !='' V"\0Y0
begin aT!'}GjL
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere `{k"8#4:qA
end ,l YE
else IYn]U4P.
begin tG vG
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' K_)eWf0a
end ~c^>54
我们可以直接写成 2WX7nK;I
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere klg25 #t
2、收缩数据库 . o7m!
--重建索引 )c n+1R
DBCC REINDEX f"7O "6
DBCC INDEXDEFRAG -}O1dEn.
--收缩数据和日志 *4+3ObA
DBCC SHRINKDB F'jWV5"*
DBCC SHRINKFILE C2LL|jp*
3、压缩数据库 !tfb*@{;'
dbcc shrinkdatabase(dbname) ;<yd^Xs
4、转移数据库给新用户以已存在用户权限 *n"/a{6>
exec sp_change_users_login 'update_one','newname','oldname' dm0QcW4
go )[0T16
5、检查备份集 ,@1p$n
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' t!*+8Q!e
6、修复数据库 VE+IKj!VG0
ALTER DATABASE [dvbbs] SET SINGLE_USER Ee4&g<X.
GO /VmR<C?h
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK bM8If"
GO u6>?AW1~
ALTER DATABASE [dvbbs] SET MULTI_USER z<H~ItX,n
GO 'smWLz}
7、日志清除 |D, +P
SET NOCOUNT ON =]:> "_jN
DECLARE @LogicalFileName sysname, f$NM M
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@MaxMinutes INT, I%-
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@NewSize INT Y3Vlp/"rB"
USE tablename -- 要操作的数据库名 \j&^aAp r
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 )Ke*JJaq
@MaxMinutes = 10, -- Limit on time allowed to wrap log. w"R:\@ F
@NewSize = 1 -- 你想设定的日志文件的大小(M) 9U$EJN_G
-- Setup / initialize EEGy!bff
DECLARE @OriginalSize int v) vkn/:
SELECT @OriginalSize = size K~@Mg1R
FROM sysfiles .e_cgad :
WHERE name = @LogicalFileName %Gt.m
SELECT 'Original Size of ' + db_name() + ' LOG is ' + 035rPT7-2-
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + jDQZQ NS
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' M5xCC!
FROM sysfiles /_`lz^
WHERE name = @LogicalFileName ]T%rjsN
CREATE TABLE DummyTrans bV ZMW/w
(DummyColumn char (8000) not null) _YF%V;X
DECLARE @Counter INT, 0v9rv.Y"
@StartTime DATETIME, #dM9pc jh
@TruncLog VARCHAR(255) 6R=W}q4
SELECT @StartTime = GETDATE(), ~%YBI9$+
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' &^W|iXi#
DBCC SHRINKFILE (@LogicalFileName, @NewSize) lsJnI|
EXEC (@TruncLog) E9~Ghx.
-- Wrap the log if necessary. HuOIFv
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired .'Vww
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) F&&$Qn_+
AND (@OriginalSize * 8 /1024) > @NewSize &L^+BQ`O?
BEGIN -- Outer loop. V7/I>^X
SELECT @Counter = 0 .k,kTr$S
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) Q=]w !I\
BEGIN -- update
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INSERT DummyTrans VALUES ('Fill Log') 0{=`on;
DELETE DummyTrans qHxqQ'ks;
SELECT @Counter = @Counter + 1 ]Ux<aiY]a
END Rz.? i+
EXEC (@TruncLog) o
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END )b:7-}d
SELECT 'Final Size of ' + db_name() + ' LOG is ' + f"<O0Qw
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + |`cKD >
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' %"P,1&\^
FROM sysfiles X-wf:h?i
WHERE name = @LogicalFileName JYTP
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DROP TABLE DummyTrans 9]@A]p!
SET NOCOUNT OFF ;cQ6g`
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8、说明:更改某个表 -4cXRv]
exec sp_changeobjectowner 'tablename','dbo' L31HGH2l
9、存储更改全部表
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CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch o#skR4lwe
@OldOwner as NVARCHAR(128), >"C,@cN}B
@NewOwner as NVARCHAR(128) q#s,-u u
AS 1&-
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DECLARE @Name as NVARCHAR(128) Xwhui4'w
DECLARE @Owner as NVARCHAR(128) Z-l=\ekJ
DECLARE @OwnerName as NVARCHAR(128) v#!%GEg1r
DECLARE curObject CURSOR FOR % ClHCoyA
select 'Name' = name, v-PXZ'7~
'Owner' = user_name(uid) IyPwP*A
from sysobjects =F@Wgn,
where user_name(uid)=@OldOwner c`o7d)_Ke
order by name 0:T|S>FsAm
OPEN curObject T7#W0^tj
FETCH NEXT FROM curObject INTO @Name, @Owner N|6MP
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WHILE(@@FETCH_STATUS=0) D}mjN=Y
BEGIN s#WAR]x0x
if @Owner=@OldOwner r.BIJt)
begin !Ze5)g%H
set @OwnerName = @OldOwner + '.' + rtrim(@Name) /\hzb/
exec sp_changeobjectowner @OwnerName, @NewOwner aXoVy&x=
end aP/T<QZ~
-- select @name,@NewOwner,@OldOwner *#C+iAF|)'
FETCH NEXT FROM curObject INTO @Name, @Owner ]4pkcV
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END urjjw.wZ
close curObject XR;eY:89
deallocate curObject v^1pN>#%g
GO SF>c\eTtx
10、SQL SERVER中直接循环写入数据 o<|P9#(U"
declare @i int /|D*w^>
set @i=1 CL+}|7O(
while @i<30 8]U{;|';
begin 6,0_)O}\b
insert into test (userid) values(@i) ])nPPf
set @i=@i+1 Mw;sLsu
end l\@)y4
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小记存储过程中经常用到的本周,本月,本年函数
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Dateadd(wk,datediff(wk,0,getdate()),-1) FgB&b
Dateadd(wk,datediff(wk,0,getdate()),6) [x,>?~6ek
Dateadd(mm,datediff(mm,0,getdate()),0) Np"exFqN k
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) !lj| cT9
Dateadd(yy,datediff(yy,0,getdate()),0) ~,i-8jl,
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) LILQ\I<<'
上面的SQL代码只是一个时间段 a+%6B_|\
Dateadd(wk,datediff(wk,0,getdate()),-1) yge,8i)c
Dateadd(wk,datediff(wk,0,getdate()),6) !;KCU^9
就是表示本周时间段. T-U}QM_e
下面的SQL的条件部分,就是查询时间段在本周范围内的: O4og?h>
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6)
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而在存储过程中 "-vW,7y
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) v%iof1 T'
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) N-e @j4WU