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。 z-Hkz
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一、基础 gduxA/aT
1、说明:创建数据库 |HgfV@Han
CREATE DATABASE database-name oS!/|#mn
2、说明:删除数据库 S:97B\u`
drop database dbname D0%FELG05
3、说明:备份sql server 0VG=?dq
--- 创建 备份数据的 device )1z4q`
USE master O)<r>vqe}
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' 9".Uc8^p/F
--- 开始 备份 8&Wx@QI
BACKUP DATABASE pubs TO testBack "Z9^}
4、说明:创建新表 wiV&xl
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 5Fe-=BX(
根据已有的表创建新表: Qx.jCy@
A:create table tab_new like tab_old (使用旧表创建新表) 4!'1/3cY
B:create table tab_new as select col1,col2... from tab_old definition only $MT}l
5、说明:删除新表
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drop table tabname %F3}/2
6、说明:增加一个列
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Alter table tabname add column col type Ar~{= X
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。 \]a uSO
7、说明:添加主键: Alter table tabname add primary key(col) PJwEA
说明:删除主键: Alter table tabname drop primary key(col) .HD ebi
8、说明:创建索引:create [unique] index idxname on tabname(col....) "o==4?*L
删除索引:drop index idxname =tq7z =k
注:索引是不可更改的,想更改必须删除重新建。 Lw*1 .~
9、说明:创建视图:create view viewname as select statement {{zua-F
删除视图:drop view viewname r`>~Lp`
10、说明:几个简单的基本的sql语句 J[+Tj@n'
选择:select * from table1 where 范围 TAAR'Jz S
插入:insert into table1(field1,field2) values(value1,value2) >C^/,/%v
删除:delete from table1 where 范围 0#
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更新:update table1 set field1=value1 where 范围 P%jkKE?B4
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! (\uAAW"
排序:select * from table1 order by field1,field2 [desc] Ltg-w\?]
总数:select count as totalcount from table1 6=BZ~ed
求和:select sum(field1) as sumvalue from table1 P=pY8X:
平均:select avg(field1) as avgvalue from table1 'Z$jBL
最大:select max(field1) as maxvalue from table1 Zih5/I
最小:select min(field1) as minvalue from table1 g5<ZS3tQ
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11、说明:几个高级查询运算词 r&/D~g\"|[
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A: UNION 运算符 v['AB4
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 af^@
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B: EXCEPT 运算符 Yoe les-
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 nO:HB.&@
C: INTERSECT 运算符 CH#kvR2
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 ZK!4>OuH`
注:使用运算词的几个查询结果行必须是一致的。 / (.'*biQ
12、说明:使用外连接 >+f'!*%7He
A、left outer join: F]Pul|.l
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 lk~dgky@
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c q"l>`KCG`
B:right outer join: HMQ'b(a'
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 {'&8`d
C:full outer join: B~BUWWMfp
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 +E)e1:8
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二、提升 8}J(c=4Gk
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) .8%vd
法一:select * into b from a where 1<>1 ?^ eJ:
法二:select top 0 * into b from a f5N<3 m=
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) -
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insert into b(a, b, c) select d,e,f from b; 'H
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3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) Hc"N&
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insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 JH-nvv
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. krwf8!bI
4、说明:子查询(表名1:a 表名2:b) )*+u\x_Hx
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) Jn60i6/
5、说明:显示文章、提交人和最后回复时间 wo$|~
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select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b (kdC1,E
6、说明:外连接查询(表名1:a 表名2:b)
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select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c CARq^xI-
7、说明:在线视图查询(表名1:a ) i{4'cdr?
select * from (SELECT a,b,c FROM a) T where t.a > 1; '%3u%;"
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 ?F!W#
select * from table1 where time between time1 and time2 XZ!cW=bqS
select a,b,c, from table1 where a not between 数值1 and 数值2 7- (>"75Q|
9、说明:in 的使用方法 e|35|I '
select * from table1 where a [not] in ('值1','值2','值4','值6') zmdWVFVv
10、说明:两张关联表,删除主表中已经在副表中没有的信息 YcEtgpz@
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) <b3x(/
11、说明:四表联查问题: ;cnnqT6
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 ..... Ae3,W
12、说明:日程安排提前五分钟提醒 Am]2@ESUP
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 VoWA tNU
13、说明:一条sql 语句搞定数据库分页 m]Hb+Y=;h
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 Hs.6;|0%
14、说明:前10条记录 r=xTs,xx
select top 10 * form table1 where 范围 MP_A<F
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.) |2[S/8g!
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) )Fw
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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 Dg1kbO=2
(select a from tableA ) except (select a from tableB) except (select a from tableC) nmTm(?yE
17、说明:随机取出10条数据 t*5z1T?
select top 10 * from tablename order by newid() @G7w(>_T3
18、说明:随机选择记录 QZ6[*_Z6
select newid() Ax :3}
19、说明:删除重复记录 6yy|V~5
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) <=#lRZW[z
20、说明:列出数据库里所有的表名 )R8%wk?2
select name from sysobjects where type='U' Ompi~
21、说明:列出表里的所有的 "m
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select name from syscolumns where id=object_id('TableName') >SY2LmV'a
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。 F]/L!
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 u4`mQ6
显示结果: "``W6W-(
type vender pcs 3(cU)
电脑 A 1 A%.J%[MVz
电脑 A 1 Q:'qw#P/C
光盘 B 2 'Wo?%n
光盘 A 2 ocb%&m;i
手机 B 3 VyB\]EBu
手机 C 3 -G(3Y2
23、说明:初始化表table1 4Z<]4:o
TRUNCATE TABLE table1 Kx(76_XD
24、说明:选择从10到15的记录 tn(?nQN3
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc %AzPAWcN
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三、技巧 #rSasucr
1、1=1,1=2的使用,在SQL语句组合时用的较多 61ON
"where 1=1" 是表示选择全部 "where 1=2"全部不选, c+}!yH$
如: U)O?|
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if @strWhere !='' Gp?ToS2^d
begin U-wq- GT
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere M63s(f
end 7.w*+Z>z
else Wq=ZU\Y
begin lGD%R'}
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' ~%cSckE
end BXQ\A~P\
我们可以直接写成 CVyx lc>
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere EqNz L*E
2、收缩数据库 yv6Zo0s<J
--重建索引 mq|A8>g
DBCC REINDEX BK`Q)[
DBCC INDEXDEFRAG 0~PXa(!^K
--收缩数据和日志 I?^Q084
DBCC SHRINKDB 3D 4]yR5
DBCC SHRINKFILE _WRR
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3、压缩数据库 4Zv.[V]iOO
dbcc shrinkdatabase(dbname) kxr6sO~
4、转移数据库给新用户以已存在用户权限 =8$(i[;6w
exec sp_change_users_login 'update_one','newname','oldname' .(P@Bl]XJ
go .!7Fe)(x
5、检查备份集 $M}k%Z
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' Ak%no3:9
6、修复数据库 =hZ&66
ALTER DATABASE [dvbbs] SET SINGLE_USER ft~|
GO CP F>^Mp#
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK xdFP$Y~ogy
GO }"g21-T^
ALTER DATABASE [dvbbs] SET MULTI_USER i?&4SG+2~K
GO Z>>gXh<e[
7、日志清除 8|S1|t,
SET NOCOUNT ON FcA)RsMI*
DECLARE @LogicalFileName sysname, Qwp\)jVi
@MaxMinutes INT, :>AW@SoTp
@NewSize INT qb>|n1F_
USE tablename -- 要操作的数据库名 =:CGl
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 h;4y=UU
@MaxMinutes = 10, -- Limit on time allowed to wrap log. P!)7\.7
@NewSize = 1 -- 你想设定的日志文件的大小(M) eCPKpVhP
-- Setup / initialize <ZHY3
DECLARE @OriginalSize int A9fjMnw
SELECT @OriginalSize = size m-Z'K_oQ
FROM sysfiles c1)BGy li
WHERE name = @LogicalFileName X1
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SELECT 'Original Size of ' + db_name() + ' LOG is ' + )$lSG}WD
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + @Le ^- v4
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' n !CP_
FROM sysfiles : e0R7sj
WHERE name = @LogicalFileName ]sm0E@ 1
CREATE TABLE DummyTrans Y7b,td1
(DummyColumn char (8000) not null) ;S{Ld1;
DECLARE @Counter INT, ]$?zT`>(F
@StartTime DATETIME, m"?'hR2
@TruncLog VARCHAR(255) \U<F\i
SELECT @StartTime = GETDATE(), A^= Hu,"e
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' U:pLnNp`
DBCC SHRINKFILE (@LogicalFileName, @NewSize) fRv
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EXEC (@TruncLog) C,VqT6E<
-- Wrap the log if necessary. O_s9
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired Y|x6g(b
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) WW8YB"
AND (@OriginalSize * 8 /1024) > @NewSize 6/V{>MTZg
BEGIN -- Outer loop. Qn'r+X5t
SELECT @Counter = 0 3
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WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) l b1sV
BEGIN -- update [6RV'7`Abj
INSERT DummyTrans VALUES ('Fill Log') a?U%l 9F
DELETE DummyTrans _I
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SELECT @Counter = @Counter + 1 >r4Y\"/j
END 8Jib|#!
EXEC (@TruncLog) 'wT./&Z
END =xlYQ}-(a
SELECT 'Final Size of ' + db_name() + ' LOG is ' + gR_b~^
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + {%+3D,$)
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' DoCQFSL
FROM sysfiles dZ]\1""#H
WHERE name = @LogicalFileName ^$&"<
DROP TABLE DummyTrans c@ZkX]g
SET NOCOUNT OFF 1TD&&EC
8、说明:更改某个表 i-"h"nF"
exec sp_changeobjectowner 'tablename','dbo' gne#v
9、存储更改全部表 Z>MJ0J76]
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch
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@OldOwner as NVARCHAR(128), T0np<l]A
@NewOwner as NVARCHAR(128) EDa08+Y
AS (Aov}I+
DECLARE @Name as NVARCHAR(128) 9q0,K" x)
DECLARE @Owner as NVARCHAR(128) -SC2Zgi)A
DECLARE @OwnerName as NVARCHAR(128) 1 [~|
DECLARE curObject CURSOR FOR x1hs19s
select 'Name' = name, JG+g88
'Owner' = user_name(uid) Z+"E*
from sysobjects 5x1jLPl'
where user_name(uid)=@OldOwner ).O2_<&?F
order by name wJ]$'c3
OPEN curObject %.atWX`b
FETCH NEXT FROM curObject INTO @Name, @Owner D!D%.
WHILE(@@FETCH_STATUS=0) ]TTJr C:
BEGIN [(e`b
if @Owner=@OldOwner 8L9S^ '
begin D^R! |K/
set @OwnerName = @OldOwner + '.' + rtrim(@Name) HNHhMi`w
exec sp_changeobjectowner @OwnerName, @NewOwner t&Y^W <
end V@+<,tjq
-- select @name,@NewOwner,@OldOwner l<)JAT;P
FETCH NEXT FROM curObject INTO @Name, @Owner zk^7gx3x
END ow>[#.ua
close curObject /+JP~K
deallocate curObject Zkb,v!l
GO 4S{l>/I
10、SQL SERVER中直接循环写入数据 )V+Dqh,-g
declare @i int :EldP,s#x%
set @i=1 ,9l!fT?iH
while @i<30 ;xkf?|
begin YWBP'Mo
insert into test (userid) values(@i) fY+ .#V
set @i=@i+1 px(1Ppb9
end |#khwH
小记存储过程中经常用到的本周,本月,本年函数 bl=*3qB
Dateadd(wk,datediff(wk,0,getdate()),-1) MgK(gL/&[
Dateadd(wk,datediff(wk,0,getdate()),6) [#@p{[ ?r
Dateadd(mm,datediff(mm,0,getdate()),0) HjF'~n
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) NYV0<z@M2M
Dateadd(yy,datediff(yy,0,getdate()),0) J`D<
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) ;uo|4?E:\(
上面的SQL代码只是一个时间段 K
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Dateadd(wk,datediff(wk,0,getdate()),-1) O6/=/-?N=c
Dateadd(wk,datediff(wk,0,getdate()),6) 8'_
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就是表示本周时间段. VTX'f2\
下面的SQL的条件部分,就是查询时间段在本周范围内的: ,vY
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Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) B xN#Nk~
而在存储过程中
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select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) 1MzB?[gx
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) eEds-&_