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。 M6[O>z
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一、基础 3D,tnn+J
1、说明:创建数据库 r"7 !J[u
CREATE DATABASE database-name |>JRJ"CFE
2、说明:删除数据库 6m9\0)R
drop database dbname 0LWV.OIIC
3、说明:备份sql server Vvn~G.&)
--- 创建 备份数据的 device
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USE master w~AO;X*Ke"
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' <?rdhx
--- 开始 备份 9WL$3z'*
BACKUP DATABASE pubs TO testBack |i(@1 l
4、说明:创建新表 _k)EqPYu@
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) o^d
根据已有的表创建新表: }F_=.w0
A:create table tab_new like tab_old (使用旧表创建新表) fHF*#
B:create table tab_new as select col1,col2... from tab_old definition only :Q;mgHTNz
5、说明:删除新表 s8*Q@0
drop table tabname Z(ToemF)hi
6、说明:增加一个列 x,<|<W5<%
Alter table tabname add column col type ZjgfkZAS
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 1?y
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7、说明:添加主键: Alter table tabname add primary key(col) [TmZ\t!5$
说明:删除主键: Alter table tabname drop primary key(col) ?J5E.7o
8、说明:创建索引:create [unique] index idxname on tabname(col....) aslb^
删除索引:drop index idxname *)T7DN8
注:索引是不可更改的,想更改必须删除重新建。 Zu ![v0
9、说明:创建视图:create view viewname as select statement E`q)vk
删除视图:drop view viewname mN"g~o*
10、说明:几个简单的基本的sql语句 xQs._YY
选择:select * from table1 where 范围 _W BWFGj
插入:insert into table1(field1,field2) values(value1,value2) Tu=~iQ
删除:delete from table1 where 范围 p v*f]Yzx
更新:update table1 set field1=value1 where 范围 'DB'lP
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! $btk48a 7
排序:select * from table1 order by field1,field2 [desc] -aM7>YR
总数:select count as totalcount from table1 !h+VbZ
求和:select sum(field1) as sumvalue from table1 r4pR[G._
平均:select avg(field1) as avgvalue from table1 HA;G{[X
最大:select max(field1) as maxvalue from table1 _^NL{R/
最小:select min(field1) as minvalue from table1 \x~},!l
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11、说明:几个高级查询运算词 'dd[=vzK
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A: UNION 运算符 3Ebkq[/*%
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。 4nD U-P#f
B: EXCEPT 运算符 CQET
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。 82w=t
C: INTERSECT 运算符 $+w -r#,
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 90
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注:使用运算词的几个查询结果行必须是一致的。 ~=c[?:
12、说明:使用外连接 N'M+Z=!
A、left outer join: '8"$: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。 'n7Ld6%1
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 ?`=r@
B:right outer join: F'JceU
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。 a*{ -r]
C:full outer join: XjJ[7"hs*
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。 z5IdYF?
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二、提升 ;
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1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) Y2P%0
法一:select * into b from a where 1<>1 l#!6
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法二:select top 0 * into b from a +Am\jsq
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) KOVR=``"/
insert into b(a, b, c) select d,e,f from b; R}0!F2
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)
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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 f VpE&F
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. {h}e 9
4、说明:子查询(表名1:a 表名2:b) Q1u/QA:z7
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) >WYradLUi
5、说明:显示文章、提交人和最后回复时间 4
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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 nB#XQ8Nzx^
6、说明:外连接查询(表名1:a 表名2:b) nrRP1`!]T
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c ;Km74!.e7
7、说明:在线视图查询(表名1:a ) f]]UNS$AYQ
select * from (SELECT a,b,c FROM a) T where t.a > 1; nQ^ c{Bm:
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 yq\p%z$:
select * from table1 where time between time1 and time2 |eFce/
select a,b,c, from table1 where a not between 数值1 and 数值2 sB%QqFRP
9、说明:in 的使用方法 vuNq7V*}
select * from table1 where a [not] in ('值1','值2','值4','值6') NekPl/4
10、说明:两张关联表,删除主表中已经在副表中没有的信息 |E9iG
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) -gy@sSfvkv
11、说明:四表联查问题: K_CE.8G&{
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 ..... iCh,7I,m
12、说明:日程安排提前五分钟提醒 6@geakq
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 K_[B@( Xl
13、说明:一条sql 语句搞定数据库分页 5!iBKOl#D
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 a X:,1^
14、说明:前10条记录 /nVGr]t_pj
select top 10 * form table1 where 范围 |lVoL.Z,0
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.) _*LgpZ-2(
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) W60C$*h
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 -DE?L,9X9
(select a from tableA ) except (select a from tableB) except (select a from tableC) ;n;bap
17、说明:随机取出10条数据 Eh/Z4pzT
select top 10 * from tablename order by newid() eaCh;IpIf
18、说明:随机选择记录 !5=S2<UX
select newid() }J|Pd3Q Sf
19、说明:删除重复记录 I&|J +B?#
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) qfl #ki`,
20、说明:列出数据库里所有的表名 `w#p8vR
select name from sysobjects where type='U' 31k2X81;a
21、说明:列出表里的所有的 Tt\G y
select name from syscolumns where id=object_id('TableName') (|.rEaTA[1
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 oS Apa
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type O#B2XoZa+
显示结果: OCN@P+L3q
type vender pcs wJu,N(U
电脑 A 1 vC>8:3Zaq
电脑 A 1 8AuOe7D9A
光盘 B 2 Q,<V)
光盘 A 2 VVDd39q
手机 B 3 oeIza<:=R
手机 C 3 o=y0=,:a?9
23、说明:初始化表table1 < r7s,][&
TRUNCATE TABLE table1 o-r00H|
24、说明:选择从10到15的记录 Z@QJ5F1y
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc ylwh_&>2
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三、技巧 PQA}_o
1、1=1,1=2的使用,在SQL语句组合时用的较多 s2t9+ZA+s
"where 1=1" 是表示选择全部 "where 1=2"全部不选, qpXsQim$~
如: m9 D'yXZ
if @strWhere !='' ]c~W$h+F
begin ,AEaW
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere Auk#pO#
end d@e2+3<
else 5!*@gn
begin Z[?zaQ$
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' 1&#qq*{
end 1?,1EYT"
我们可以直接写成 -wrVhCd~g]
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere j$Wd[Ja+O
2、收缩数据库 8D6rShx =
--重建索引 $v0beN6MG
DBCC REINDEX =dDr:Y<@*
DBCC INDEXDEFRAG r0(* ]K:.
--收缩数据和日志 ]o3K
DBCC SHRINKDB EaUO>S
DBCC SHRINKFILE #d;/Me
3、压缩数据库 4"~l^yK
dbcc shrinkdatabase(dbname) ^< wn
4、转移数据库给新用户以已存在用户权限 =Cg1I\
exec sp_change_users_login 'update_one','newname','oldname' L wP
go K0C3s
5、检查备份集 x_$`#m{hL5
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' Zj5B}[,l\
6、修复数据库 G e+T[
ALTER DATABASE [dvbbs] SET SINGLE_USER ibn(eu<uW
GO M"
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DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK q!4eVg*
GO ;<N%D=;}@
ALTER DATABASE [dvbbs] SET MULTI_USER $~r_&1
GO <tT.m[q g
7、日志清除 Z+g9!@'a
SET NOCOUNT ON /lDei}
DECLARE @LogicalFileName sysname, @M&qH[tK-A
@MaxMinutes INT, C q)Cwc[H
@NewSize INT ckdXla
USE tablename -- 要操作的数据库名 y ]D[JX[
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 U\GuCw
@MaxMinutes = 10, -- Limit on time allowed to wrap log. ,4H/>yPw
@NewSize = 1 -- 你想设定的日志文件的大小(M) H?cJ'Q,5
-- Setup / initialize iph}!3f
DECLARE @OriginalSize int ?'RB'o~
SELECT @OriginalSize = size lFZl}x
FROM sysfiles Q%!Dk0-)
WHERE name = @LogicalFileName %_%BbQf
SELECT 'Original Size of ' + db_name() + ' LOG is ' + E(g$f.9
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + FL E3LH
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' o8h`9_
FROM sysfiles $(+#$F<eo+
WHERE name = @LogicalFileName pj#l s
CREATE TABLE DummyTrans 4=qZ Z>[t
(DummyColumn char (8000) not null) 4~i?xo=;v
DECLARE @Counter INT, 6<mlx'
@StartTime DATETIME, E4,
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@TruncLog VARCHAR(255) M2pFXU?]
SELECT @StartTime = GETDATE(), Nk;ywC"e;
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' C2C1 @=w
DBCC SHRINKFILE (@LogicalFileName, @NewSize) ;LqpX!Pi
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EXEC (@TruncLog) mnL+@mm
-- Wrap the log if necessary. nZ %%{#T7
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired 5jAS1XG
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) %00cC~}4
AND (@OriginalSize * 8 /1024) > @NewSize 2;ju/9x
BEGIN -- Outer loop. "/nbcQ*s*E
SELECT @Counter = 0 %&j\:X~A
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) sf"vi i,1A
BEGIN -- update t-Uo
INSERT DummyTrans VALUES ('Fill Log') #\Zr$?t|V
DELETE DummyTrans eI,H
SELECT @Counter = @Counter + 1 2{<o1x,Ym
END \![ p-mW{
EXEC (@TruncLog) l1vI
END DR7 JEE
SELECT 'Final Size of ' + db_name() + ' LOG is ' + ?azcWf z0
CONVERT(VARCHAR(30),size) + ' 8K pages or ' +
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CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' 4 (XV)QR
FROM sysfiles qL4s@<|~
WHERE name = @LogicalFileName Z rv:uEl
DROP TABLE DummyTrans o 3JSh=
SET NOCOUNT OFF "h-ZwL
8、说明:更改某个表 ==AmL]*
exec sp_changeobjectowner 'tablename','dbo' pp@O6
9、存储更改全部表 '<{Jlz(u9
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch yw1-4*$c
@OldOwner as NVARCHAR(128), a:Nf+t
@NewOwner as NVARCHAR(128) |]5`T9K@b#
AS "x3x$JQZy
DECLARE @Name as NVARCHAR(128) D)tL}X$
DECLARE @Owner as NVARCHAR(128) 0.)q5B`
DECLARE @OwnerName as NVARCHAR(128) )H(i)$I
DECLARE curObject CURSOR FOR iDWM-Ytx
select 'Name' = name, CaC \\5wl
'Owner' = user_name(uid) $,zW0</P*l
from sysobjects V1haAP[#
where user_name(uid)=@OldOwner z(Z7[#.
order by name R@){=8%z
OPEN curObject dhjX[7Bl9
FETCH NEXT FROM curObject INTO @Name, @Owner SY.ZEJcv
WHILE(@@FETCH_STATUS=0) <nTZs`$LwL
BEGIN zx5#eMD
if @Owner=@OldOwner WPAT\Al&AE
begin \/64Xv3L0
set @OwnerName = @OldOwner + '.' + rtrim(@Name) +)LCYDRV7
exec sp_changeobjectowner @OwnerName, @NewOwner }U '
end mLx=Zes:.
-- select @name,@NewOwner,@OldOwner bYO['ORr@
FETCH NEXT FROM curObject INTO @Name, @Owner pu5%$}dBE
END IhRdn1&
close curObject zf>*\pZE
deallocate curObject ;;6$d{
GO Lt
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10、SQL SERVER中直接循环写入数据 `<{LW>Lb
declare @i int "
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set @i=1 />N# PF
while @i<30 vVP.9(
begin yi:}UlO
insert into test (userid) values(@i) J/IRCjQ}
set @i=@i+1 8L+A&^qx
end y^z
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小记存储过程中经常用到的本周,本月,本年函数 1nw\?r2
Dateadd(wk,datediff(wk,0,getdate()),-1) TF9A4
Dateadd(wk,datediff(wk,0,getdate()),6) et"Pb_-U
Dateadd(mm,datediff(mm,0,getdate()),0) bB>.dC
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) xS>vmnW
Dateadd(yy,datediff(yy,0,getdate()),0) sF>O=F-7
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) ?GlXxx=eV
上面的SQL代码只是一个时间段 W*%(J$E
Dateadd(wk,datediff(wk,0,getdate()),-1) ]&N>F8.L+
Dateadd(wk,datediff(wk,0,getdate()),6) TB-dV'w
就是表示本周时间段. XhA tf@n
下面的SQL的条件部分,就是查询时间段在本周范围内的: I{h KN V
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) 0'
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而在存储过程中 F]t=5
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select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) +u&[ j/
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) F-$!e?,H