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。 }9 ]7V <
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一、基础 t`Rbn{
1、说明:创建数据库 `GSl}A
CREATE DATABASE database-name qu\U^F
2、说明:删除数据库 h$#PboLd
drop database dbname EiDnUL(W7h
3、说明:备份sql server Ng2Z7k
--- 创建 备份数据的 device ?[|A sw1t
USE master "(iDUl
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' au]W*;x
--- 开始 备份 V,%K"b=
BACKUP DATABASE pubs TO testBack V|TD+7.`QB
4、说明:创建新表 w9StW94p
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) I/%L,XyRI
根据已有的表创建新表: 29l bOi
A:create table tab_new like tab_old (使用旧表创建新表) RG=i74a
B:create table tab_new as select col1,col2... from tab_old definition only voFg6zoV_
5、说明:删除新表 kxR!hA8wv4
drop table tabname dOK]Su
6、说明:增加一个列 }lXor~_i
Alter table tabname add column col type DS9-i2
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。 2r!- zEV
7、说明:添加主键: Alter table tabname add primary key(col) qnb/zr)p
说明:删除主键: Alter table tabname drop primary key(col) hE
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8、说明:创建索引:create [unique] index idxname on tabname(col....) oJ tmd}
删除索引:drop index idxname PC\p>6xT
注:索引是不可更改的,想更改必须删除重新建。 ?-~<Vc*
9、说明:创建视图:create view viewname as select statement }(!rB#bf
删除视图:drop view viewname liqVfB%
10、说明:几个简单的基本的sql语句 PI@?I&Bo
选择:select * from table1 where 范围 A<^X P-Nrp
插入:insert into table1(field1,field2) values(value1,value2) 0Y'ow=8M
删除:delete from table1 where 范围 `t\\O
更新:update table1 set field1=value1 where 范围 AiL80W^=d)
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! v0TbQ
排序:select * from table1 order by field1,field2 [desc] >oN Wf
总数:select count as totalcount from table1 }]M'f:%b
求和:select sum(field1) as sumvalue from table1 BnfuI
平均:select avg(field1) as avgvalue from table1 %O!TS_~9
最大:select max(field1) as maxvalue from table1 W56VA>ia
最小:select min(field1) as minvalue from table1 >l #D9%
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11、说明:几个高级查询运算词 R!
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A: UNION 运算符 L]H'
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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。 N`{6<Z0
B: EXCEPT 运算符 ZNl1e'
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。 >K&chg@Hv
C: INTERSECT 运算符 .'. bokl/
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。 ?p/}eRgi
注:使用运算词的几个查询结果行必须是一致的。 tqCwbi
12、说明:使用外连接 h4=mGJpm
A、left outer join: 4cqf=
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。 itE/QB
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 W]Nc6B*gI
B:right outer join: >j7]gi(
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。 t3g+>U_m
C:full outer join: .beqfcj"
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。 E^gN]Z"O
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二、提升 2.=G
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) >6[d&SM6
法一:select * into b from a where 1<>1 $-|$4lrS
法二:select top 0 * into b from a {2QP6X sJ
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) 0~+*$W
insert into b(a, b, c) select d,e,f from b; B'mUDW8\D
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) Q^=0p0
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 6nJQP a
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. vC^{,?@
4、说明:子查询(表名1:a 表名2:b) a\~118 !
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) yye5GVY$
5、说明:显示文章、提交人和最后回复时间 !Eb|AHa
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b ? HNuffk
6、说明:外连接查询(表名1:a 表名2:b) `>b,'u6F
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c Qg]A^{.1
7、说明:在线视图查询(表名1:a ) !G6h~`[
select * from (SELECT a,b,c FROM a) T where t.a > 1; ,j9? 9Z7R
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 ._t1eb`m{
select * from table1 where time between time1 and time2 {-MjsBR
select a,b,c, from table1 where a not between 数值1 and 数值2 fFoZ!H
9、说明:in 的使用方法 19-V;F@;
select * from table1 where a [not] in ('值1','值2','值4','值6') *0?@/2&
10、说明:两张关联表,删除主表中已经在副表中没有的信息 bo@
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delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) Jh<s '&FR
11、说明:四表联查问题: OSLZ7B^
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 ..... ^ fyue~9u
12、说明:日程安排提前五分钟提醒 s&'FaqE
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 | lZJt
13、说明:一条sql 语句搞定数据库分页 3TZ:
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 !! )W`
14、说明:前10条记录 mhOgv\?
select top 10 * form table1 where 范围 R/Z7}Q W
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.) -j2y#aP
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) AlG5n'
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 i~AReJxt7
(select a from tableA ) except (select a from tableB) except (select a from tableC) Gg]Jp:GF
17、说明:随机取出10条数据 %rgW}Z5
select top 10 * from tablename order by newid() #,#:{&H
18、说明:随机选择记录 fBh/$
select newid() +]zRn
19、说明:删除重复记录 #D%6b
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) XN>bv|*q
20、说明:列出数据库里所有的表名 BjsTHS&
select name from sysobjects where type='U' Ww\ WuaY
21、说明:列出表里的所有的 [)dIt@Y&j
select name from syscolumns where id=object_id('TableName') F |R7hqf
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。 <2]D3,.g.
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 _ WPt
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显示结果:
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type vender pcs U 8p %MFD
电脑 A 1 =yM%#{t&W
电脑 A 1 80T2EN:$
光盘 B 2 lUA-ug! ^
光盘 A 2 _d!o,=}
手机 B 3 $-~"G,;F
手机 C 3 ,nCvA%B!
23、说明:初始化表table1 CWRB/WH:
TRUNCATE TABLE table1 ~b!la
24、说明:选择从10到15的记录 tJn"$A^N
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc 6O.kKhk
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三、技巧 (i1x<
1、1=1,1=2的使用,在SQL语句组合时用的较多 WHOX<YJs
"where 1=1" 是表示选择全部 "where 1=2"全部不选, "frioi`a2
如: -^(KGu&L&u
if @strWhere !='' ='=4tj=z
begin {&^PDa|nD
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere >3ZhPvE-p'
end 9Li&0E
else ;+|Z5+7!6
begin XGbpH<
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' 'Ha> >2M
end mk^,{D
我们可以直接写成 dKC*QHU
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere tLN^k;w
2、收缩数据库 3 =c#LUA`
--重建索引 z$}9f*W}B
DBCC REINDEX zK1]o-wSAT
DBCC INDEXDEFRAG I1l^0@J
--收缩数据和日志 \%bJXTK&W
DBCC SHRINKDB K/*"U*9Kv
DBCC SHRINKFILE GvgTbCxnN
3、压缩数据库 r}^1dO
dbcc shrinkdatabase(dbname) afna7TlS
4、转移数据库给新用户以已存在用户权限 5 r_Z3/%
exec sp_change_users_login 'update_one','newname','oldname' Ovj^
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go X%&7-PO
5、检查备份集 S
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RESTORE VERIFYONLY from disk='E:\dvbbs.bak' Jc}6kFgO6
6、修复数据库 FE^/us7r
ALTER DATABASE [dvbbs] SET SINGLE_USER GG<0k\RN
GO >;Vfs{Z(q
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK &7>]# *
GO .taP2^2Z
ALTER DATABASE [dvbbs] SET MULTI_USER G!=(^G@J;
GO
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7、日志清除 qsXkm4
SET NOCOUNT ON 'W4v>0
DECLARE @LogicalFileName sysname, }Y BuS3{
@MaxMinutes INT, )!cucY
@NewSize INT x3#:C=
USE tablename -- 要操作的数据库名 T0"nzukd
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 >3B{sn}
@MaxMinutes = 10, -- Limit on time allowed to wrap log. 7CSz
@NewSize = 1 -- 你想设定的日志文件的大小(M) izGU&VeB
-- Setup / initialize }$L1A
DECLARE @OriginalSize int WQze|b%
SELECT @OriginalSize = size Y<(7u`F
FROM sysfiles }7b{ZbDI
WHERE name = @LogicalFileName eyp_.1C~
SELECT 'Original Size of ' + db_name() + ' LOG is ' + IDD`N{EA
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + 2yZ~j_AF[
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' m ie~.
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FROM sysfiles t']/2m.&p
WHERE name = @LogicalFileName %t!r
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CREATE TABLE DummyTrans vV$^`WY4
(DummyColumn char (8000) not null) TOKt{`2}
DECLARE @Counter INT, ZI qXkD
@StartTime DATETIME, *{j;LA.BR#
@TruncLog VARCHAR(255) <Opw"yY&q]
SELECT @StartTime = GETDATE(), (|o@
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' \lQI;b;$
DBCC SHRINKFILE (@LogicalFileName, @NewSize) pc@mQI
EXEC (@TruncLog) y7CO%SA
-- Wrap the log if necessary. vE8'B^h1
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired &a e!lB
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) F.i}&UQ%
AND (@OriginalSize * 8 /1024) > @NewSize ~*y7%L4B
BEGIN -- Outer loop. pY3/AO=
SELECT @Counter = 0 .d[^&<^
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) cJ@fJ|
BEGIN -- update $joGda
INSERT DummyTrans VALUES ('Fill Log') 1@ &J"*
DELETE DummyTrans R@5eHP^
SELECT @Counter = @Counter + 1 DNgh#!\X
END wb(S7OsMO
EXEC (@TruncLog) s_RK x)w@
END E<u(Yw6=
SELECT 'Final Size of ' + db_name() + ' LOG is ' + }fkdv6mz
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + ,Nhv#U<$
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' ^c(r4#}$"
FROM sysfiles Pi |Z\j)
WHERE name = @LogicalFileName 1y6<gptx
DROP TABLE DummyTrans ht L1aQ.
SET NOCOUNT OFF hEZo{0:b"
8、说明:更改某个表 9I
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exec sp_changeobjectowner 'tablename','dbo' 50Gu~No6
9、存储更改全部表 `$FX%p
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch eFS$ ;3FP1
@OldOwner as NVARCHAR(128), He4HIZ
@NewOwner as NVARCHAR(128) 0-{E% k
AS $kHXt]fU
DECLARE @Name as NVARCHAR(128) 7t#Q8u?
DECLARE @Owner as NVARCHAR(128) wme#8/eUk
DECLARE @OwnerName as NVARCHAR(128) 4guR8 elM
DECLARE curObject CURSOR FOR t\
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select 'Name' = name, X(Mpg[,N"
'Owner' = user_name(uid) w/*#TDR
from sysobjects m-tn|m!J
where user_name(uid)=@OldOwner btnD+O66<
order by name <oT1&C{
OPEN curObject :=+YZ|&j
FETCH NEXT FROM curObject INTO @Name, @Owner bx{njo1Mr
WHILE(@@FETCH_STATUS=0) L'`Au/%S}
BEGIN LJb=9tp~
if @Owner=@OldOwner 4:Ju|g]O
begin :k`Qj(7S
set @OwnerName = @OldOwner + '.' + rtrim(@Name) V4}jv7>A
exec sp_changeobjectowner @OwnerName, @NewOwner 2ib,33 Z
end 1,$"'lKwt
-- select @name,@NewOwner,@OldOwner X[$|I9
FETCH NEXT FROM curObject INTO @Name, @Owner %g5#q64
END NvTK7? v
close curObject 8rlf9m
deallocate curObject TB&IB:4)R
GO lDKyD`WKnZ
10、SQL SERVER中直接循环写入数据 ~8(Xn2
declare @i int ;8K>]T)
set @i=1 'q~<ZO
while @i<30 40`Qsv0#
begin C{nk,j
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insert into test (userid) values(@i) Akc
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set @i=@i+1 u*5}c7)uId
end 4|5;nxkGm8
小记存储过程中经常用到的本周,本月,本年函数 \4j_K*V
Dateadd(wk,datediff(wk,0,getdate()),-1) _w%:PnO
Dateadd(wk,datediff(wk,0,getdate()),6) ??P\v0E
Dateadd(mm,datediff(mm,0,getdate()),0) !t~tIJ>6
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) L
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Dateadd(yy,datediff(yy,0,getdate()),0) +_*NY~
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) ]3='TN8aQF
上面的SQL代码只是一个时间段 h@1/
Dateadd(wk,datediff(wk,0,getdate()),-1) M[O22wFs
Dateadd(wk,datediff(wk,0,getdate()),6) fJ
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就是表示本周时间段. N TDmOS\,
下面的SQL的条件部分,就是查询时间段在本周范围内的: _yH">x<
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) 3kUb cm
而在存储过程中 ,?qJAV~>
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) ]}l.*v\uK
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) c V@^<