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。 5S?yj
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一、基础 `y#C%9#
1、说明:创建数据库 \nWpV7TSN
CREATE DATABASE database-name p'4P2
2、说明:删除数据库 A&'%ou
drop database dbname &O,$l3 P
3、说明:备份sql server ZB%~>
--- 创建 备份数据的 device T1&H!
USE master :JIPF=]fc
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' t} M3F-NZ
--- 开始 备份 J|IDnCK
BACKUP DATABASE pubs TO testBack do,X{\
4、说明:创建新表 LfApVUm
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) DPx,qM#h5O
根据已有的表创建新表: J;`~
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A:create table tab_new like tab_old (使用旧表创建新表) A{%;Hd`0/
B:create table tab_new as select col1,col2... from tab_old definition only -`UlntEdZ:
5、说明:删除新表 s`YuH <8
drop table tabname F! e`i-xt
6、说明:增加一个列 TbVL71c
Alter table tabname add column col type ^'4uTbxP_!
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。 m~eWQ_a]C@
7、说明:添加主键: Alter table tabname add primary key(col) h6N}sLM{0
说明:删除主键: Alter table tabname drop primary key(col) ~B@o?8D]
8、说明:创建索引:create [unique] index idxname on tabname(col....) z-G (!]:
删除索引:drop index idxname Sq,ty{j2%
注:索引是不可更改的,想更改必须删除重新建。 Qg!*=<b
9、说明:创建视图:create view viewname as select statement zY+Et.lg]^
删除视图:drop view viewname 3(&F.&C$$
10、说明:几个简单的基本的sql语句 EYG E#C;
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选择:select * from table1 where 范围 B_2>Yt"
插入:insert into table1(field1,field2) values(value1,value2) ZB&Uhi
删除:delete from table1 where 范围 Rp*t"HSaAW
更新:update table1 set field1=value1 where 范围 ^nF$<#a
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! jYz3(mM'J
排序:select * from table1 order by field1,field2 [desc] )}!'VIe^!
总数:select count as totalcount from table1 T7~v40jn|
求和:select sum(field1) as sumvalue from table1 AUde_1hi
平均:select avg(field1) as avgvalue from table1 )S;ps
最大:select max(field1) as maxvalue from table1 "r"An"
最小:select min(field1) as minvalue from table1 ~7a BeD
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11、说明:几个高级查询运算词 9m4rNvb
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A: UNION 运算符 2*YXm>|1
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 pNFIO
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B: EXCEPT 运算符 jt--w"|-r
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 -RQQ|:O$
C: INTERSECT 运算符 ;%alZ
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。 j//wh1
注:使用运算词的几个查询结果行必须是一致的。 )du{ZWr
12、说明:使用外连接 p9WskYpm
A、left outer join: vh8Kd' y
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]6l
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 &X,)+b=
B:right outer join: %iC63)(M
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。 y03a\K5[KQ
C:full outer join: OZm[iH
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。 D.R
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二、提升 _PXo'*j
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) guXpHF=
法一:select * into b from a where 1<>1 {OrE1WHB
法二:select top 0 * into b from a RsfTUb)<
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) 5udoZ>T
insert into b(a, b, c) select d,e,f from b; F$p*G][
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) z.HNb$;
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 _
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例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. RpP[ymMZJ
4、说明:子查询(表名1:a 表名2:b) k.[) R@0%
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) NOp=/
5、说明:显示文章、提交人和最后回复时间 6G$tYfX
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b xH#a|iT?(
6、说明:外连接查询(表名1:a 表名2:b) RyWOiQk;
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c Yj/nzTVJ[
7、说明:在线视图查询(表名1:a ) !DL53DQ#
select * from (SELECT a,b,c FROM a) T where t.a > 1; nY-9
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8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 Ytwv=;h-
select * from table1 where time between time1 and time2 fZ:rz;tM
select a,b,c, from table1 where a not between 数值1 and 数值2 p!QneeA`&X
9、说明:in 的使用方法 QfWu~[
select * from table1 where a [not] in ('值1','值2','值4','值6') GSnHxs)
10、说明:两张关联表,删除主表中已经在副表中没有的信息 v^_]W3K
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) bvS\P!m\c
11、说明:四表联查问题: C,vc
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select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... ,<r 3Z$G
12、说明:日程安排提前五分钟提醒 "sX?wTag
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 SJ7=<y}[d
13、说明:一条sql 语句搞定数据库分页 <?Izfl6
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 ~<[5uZIo
14、说明:前10条记录 KqUSTR1e[
select top 10 * form table1 where 范围 @/NZ>.
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.) SSbK[aR
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) T4Gw\Z%
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 4qXRDsbCf
(select a from tableA ) except (select a from tableB) except (select a from tableC) '=G
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17、说明:随机取出10条数据 Rn_W|"
select top 10 * from tablename order by newid() lT!$\E$1
18、说明:随机选择记录 7"NJraQ6
select newid() :fKz^@mY4
19、说明:删除重复记录 YkAWKCOni
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) q.sQ Z]ty9
20、说明:列出数据库里所有的表名 Bp{`%86SE
select name from sysobjects where type='U' 7+hF;
21、说明:列出表里的所有的 YGV#.
select name from syscolumns where id=object_id('TableName') m&~Dj#%(w
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 @mRrA#E#{
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type ~'QeN%qadP
显示结果: *([)X2A@+
type vender pcs JP,(4h*
电脑 A 1 lrX0c$)
电脑 A 1 't?7.#,6O
光盘 B 2 a:^Gr%
光盘 A 2 }cK~=@7tK
手机 B 3 UQ?OD~7
手机 C 3 [67E5rk-
23、说明:初始化表table1 6 %k+0\d
TRUNCATE TABLE table1 8Y~=\(5>
24、说明:选择从10到15的记录 Cm<j*Cnl
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc S}Y|s]6
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三、技巧 "~2#!bK7
1、1=1,1=2的使用,在SQL语句组合时用的较多 )Z]y.W )
"where 1=1" 是表示选择全部 "where 1=2"全部不选, 6?.pKFBZ
如: u#@{%kPW
if @strWhere !='' 5h=TV
begin =<zSF\Zr_
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere >aC\_Mc
end kxqc6
else r{2].31'
begin D<3V#Opw
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' ie~fQ!rf
end V;hwAQbF
我们可以直接写成 [H:GKhPC`
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere sqpOS!]
2、收缩数据库 , 64t
--重建索引 ]baaOD$Z
DBCC REINDEX 1LId_vJtJ
DBCC INDEXDEFRAG m_Ac/ctf
--收缩数据和日志 Ao,!z
DBCC SHRINKDB oYh<k
DBCC SHRINKFILE [+MX$y
3、压缩数据库 .i&ZT}v3
dbcc shrinkdatabase(dbname) $K_YC~
4、转移数据库给新用户以已存在用户权限 2
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exec sp_change_users_login 'update_one','newname','oldname' DMcxa.Sd!
go [kuVQ$)
5、检查备份集 X})Imk7&E
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' .F$|j1y
6、修复数据库 H~dHVQtJZ
ALTER DATABASE [dvbbs] SET SINGLE_USER Sa1z,EP
GO e_~fJ
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK >AzWM
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GO
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ALTER DATABASE [dvbbs] SET MULTI_USER y-\A@jJC5
GO <k\H`P
7、日志清除 g;!@DVF$
SET NOCOUNT ON ?X#/1X%u:
DECLARE @LogicalFileName sysname, lHKf#|
@MaxMinutes INT, ~@4ZV
@NewSize INT yB4H3Q )
USE tablename -- 要操作的数据库名 *fH_lG%
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 ./&zO{|0]
@MaxMinutes = 10, -- Limit on time allowed to wrap log. ,s><kHJ
@NewSize = 1 -- 你想设定的日志文件的大小(M) 'uKkl(==%
-- Setup / initialize %t`SSW7I
DECLARE @OriginalSize int T~o{woq}g
SELECT @OriginalSize = size B&i0j5L
FROM sysfiles V@_-H
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WHERE name = @LogicalFileName (e8G
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SELECT 'Original Size of ' + db_name() + ' LOG is ' + ]Q4PbW
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + lTr*'fX
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' a\{1UD
FROM sysfiles PwB g
WHERE name = @LogicalFileName 8L-4}!~C
CREATE TABLE DummyTrans "<w2v'6S
(DummyColumn char (8000) not null) `e $n$Bh
DECLARE @Counter INT, ~3bZ+*H>
@StartTime DATETIME, h^A3 0f_x
@TruncLog VARCHAR(255) 2\nN4WL
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SELECT @StartTime = GETDATE(), )jlP
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@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' x9)aBB
DBCC SHRINKFILE (@LogicalFileName, @NewSize) 3xzkZ8]/
EXEC (@TruncLog) k]Alp;hVd
-- Wrap the log if necessary. mGe|8In
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired GjeUUmr
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) 9:%n=U Rd
AND (@OriginalSize * 8 /1024) > @NewSize `D)Lzm R
BEGIN -- Outer loop. ,]Ro',A&
SELECT @Counter = 0 (/SGT$#8
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) jWXR__>.
BEGIN -- update P1i*u0a
INSERT DummyTrans VALUES ('Fill Log') ^}o7*
DELETE DummyTrans *!g 24
SELECT @Counter = @Counter + 1 ;Rhb@]X
END `s`C{|wv
EXEC (@TruncLog) /}w#Jk4pD
END Pknc[h},
SELECT 'Final Size of ' + db_name() + ' LOG is ' + |As2"1_f
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + T3Frc ]6,4
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' SLtSqG7~
FROM sysfiles MCk^Tp!
WHERE name = @LogicalFileName
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DROP TABLE DummyTrans ?h!t$QQ!M
SET NOCOUNT OFF W}XYmF*_?
8、说明:更改某个表 `l>93A
exec sp_changeobjectowner 'tablename','dbo' b4Cfd?'
9、存储更改全部表 WHUT/:?f
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch o3n3URu\
@OldOwner as NVARCHAR(128), mG831v?
@NewOwner as NVARCHAR(128) )RwBg8
AS ?0rOcaTY
DECLARE @Name as NVARCHAR(128) iW|s|1mh3
DECLARE @Owner as NVARCHAR(128) ge0's+E+1
DECLARE @OwnerName as NVARCHAR(128) E
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DECLARE curObject CURSOR FOR
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select 'Name' = name, Q !9HA[Ly
'Owner' = user_name(uid) ,Z>wbMJig
from sysobjects e=t<H"&
where user_name(uid)=@OldOwner \Z)#lF|^
order by name 4!l
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OPEN curObject ?fK^&6pI
FETCH NEXT FROM curObject INTO @Name, @Owner +7Yu^&
WHILE(@@FETCH_STATUS=0) hCzjC|EO~
BEGIN JbE?a[Eg?
if @Owner=@OldOwner E-~mOYea
begin |l|_dn
set @OwnerName = @OldOwner + '.' + rtrim(@Name) 9W*.lf
exec sp_changeobjectowner @OwnerName, @NewOwner fokwW}>B[f
end fyI_
-- select @name,@NewOwner,@OldOwner mEoA#U
FETCH NEXT FROM curObject INTO @Name, @Owner b'velj3A
END
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close curObject 0Injyc*bMF
deallocate curObject F=XF]
GO "7Eo>g
10、SQL SERVER中直接循环写入数据 R?
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declare @i int 8HMo.*Ti9
set @i=1 3p=vz'
while @i<30 rdO@X9z
begin *FV0Vy
insert into test (userid) values(@i) )ll?-FZ
set @i=@i+1 7zD- ?%
end * R%.a^R
小记存储过程中经常用到的本周,本月,本年函数 &Hv;<
Dateadd(wk,datediff(wk,0,getdate()),-1) AD^X(rW
Dateadd(wk,datediff(wk,0,getdate()),6) coDjL.u
Dateadd(mm,datediff(mm,0,getdate()),0) 4d!S#zx
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) ]}Pl%.
Dateadd(yy,datediff(yy,0,getdate()),0) VS?dvZ1cC
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) 3&es]1b
上面的SQL代码只是一个时间段 U.: sK*
Dateadd(wk,datediff(wk,0,getdate()),-1) Bwjg#1 E
Dateadd(wk,datediff(wk,0,getdate()),6) #c-b}.R
就是表示本周时间段. (]2<?x*
下面的SQL的条件部分,就是查询时间段在本周范围内的: JwZ?hc
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) )S^z+3p
而在存储过程中 sf`PV}a1
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) vF"c
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) \M9h&I\7