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。 &5<lQ1
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一、基础 HY:n{=o
1、说明:创建数据库 ok'1
CREATE DATABASE database-name k=[Ro
2、说明:删除数据库 nceF4Ty
drop database dbname t60m:k4J
3、说明:备份sql server ?hYe4tc-#
--- 创建 备份数据的 device 1;V5b+b
USE master g&V.o5jIhc
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' Xqk$[peS
--- 开始 备份 oGZ9@Y)(T
BACKUP DATABASE pubs TO testBack 3-D!Z S&
4、说明:创建新表 =%p{"<
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) Ycwb1e#
根据已有的表创建新表: o hCPNm
A:create table tab_new like tab_old (使用旧表创建新表) &V
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B:create table tab_new as select col1,col2... from tab_old definition only .Pi67Kj,
5、说明:删除新表 >Ko )Z&j9W
drop table tabname rYJvI
6、说明:增加一个列 TXM.,5Dx\
Alter table tabname add column col type bUNp>H>L
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 ^9i^Ci9
7、说明:添加主键: Alter table tabname add primary key(col) * ?K=;$
说明:删除主键: Alter table tabname drop primary key(col) (ym)q#^
8、说明:创建索引:create [unique] index idxname on tabname(col....) I$&/?ns@O
删除索引:drop index idxname ` {p5SYj
注:索引是不可更改的,想更改必须删除重新建。 &k nnWm"
9、说明:创建视图:create view viewname as select statement bvG
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删除视图:drop view viewname >J1o@0tk
10、说明:几个简单的基本的sql语句 _%]H}N Q
选择:select * from table1 where 范围 %M`&}'6'
插入:insert into table1(field1,field2) values(value1,value2) P?F:x=@'|
删除:delete from table1 where 范围 !8$}]uWP
更新:update table1 set field1=value1 where 范围 moGbBkO
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! {)M4h?.2
排序:select * from table1 order by field1,field2 [desc] }`(kX] ][
总数:select count as totalcount from table1 =|V3cM4'
求和:select sum(field1) as sumvalue from table1 ~Y(M>u.+!
平均:select avg(field1) as avgvalue from table1 @?U5t1O<
最大:select max(field1) as maxvalue from table1 @tA.^k0`
最小:select min(field1) as minvalue from table1 =[,adB
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11、说明:几个高级查询运算词 C+Z"0\{o
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A: UNION 运算符 U7W ct %
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。 y.Py>GJJ1S
B: EXCEPT 运算符 C{D2mSS
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。 4}CRM# W2
C: INTERSECT 运算符 C"}x=cK
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。 xl3U
注:使用运算词的几个查询结果行必须是一致的。 !l~hO
12、说明:使用外连接 ra3WLK
A、left outer join: 8Xr3q eh+
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。 K;95M^C\O*
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 ;u%h wlo
B:right outer join: )q,}jeM8
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。 :/3`+&T^/
C:full outer join: v#6.VUAw
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。 Z6=!}a%
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二、提升 Z#Fw 1
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) /c7j@=0
法一:select * into b from a where 1<>1 E*%{Nn
法二:select top 0 * into b from a OjHBzrK
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) !\m.&lk'^
insert into b(a, b, c) select d,e,f from b; d09GD[5
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) ;KhYh S(q
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 Fri5_rxLl
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. lbPxZ'YO#
4、说明:子查询(表名1:a 表名2:b) TcC=_je460
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) 9#p^Z)[)-
5、说明:显示文章、提交人和最后回复时间 @ZVc!5J_,
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b %/s1ma6q
6、说明:外连接查询(表名1:a 表名2:b) H\^^p!^)
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c 1Nz\3]-
7、说明:在线视图查询(表名1:a ) ..!yf e"5
select * from (SELECT a,b,c FROM a) T where t.a > 1; LV[4z o]=
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 ]8^2(^3ct
select * from table1 where time between time1 and time2 XEuv
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select a,b,c, from table1 where a not between 数值1 and 数值2 Vf@/}=X *
9、说明:in 的使用方法 Zwcb5\Q
select * from table1 where a [not] in ('值1','值2','值4','值6') ovl@[>OB
10、说明:两张关联表,删除主表中已经在副表中没有的信息 yP-Dj
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delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) I}:/v$btM
11、说明:四表联查问题: *n47.(a2i
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 ..... 9.R_=
12、说明:日程安排提前五分钟提醒
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SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 M_e!s}F
13、说明:一条sql 语句搞定数据库分页 ck}y-,>,[O
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 b9U2afd
14、说明:前10条记录 ql4T@r3l}3
select top 10 * form table1 where 范围 c*h5lM'n6
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.) WRgz]=W3w
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) _w26iCnB{
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 _k}b
(select a from tableA ) except (select a from tableB) except (select a from tableC) ("aYjKk
17、说明:随机取出10条数据 * n[6H
select top 10 * from tablename order by newid() sqy5rug
18、说明:随机选择记录 RPrk]<<1
select newid() o
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19、说明:删除重复记录 L+u_153
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) #y?z2!
20、说明:列出数据库里所有的表名 "[%NXan
select name from sysobjects where type='U' ZpdM[\Q-
21、说明:列出表里的所有的 =}L[/ RL
select name from syscolumns where id=object_id('TableName') ~2qFA2
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。 !>+
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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 e0qa~5
显示结果: :sn}D~
type vender pcs hk=+t&Y<H
电脑 A 1 D&'".N,}
电脑 A 1 [:o#d`^
光盘 B 2 5!Guf?i
光盘 A 2 s)C.e# xl
手机 B 3 e#AB0-f
手机 C 3 qj|GAGrQ2
23、说明:初始化表table1 HqbTJ!a
TRUNCATE TABLE table1 u0x\5!?2
24、说明:选择从10到15的记录
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select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc Y8d%L;b[D
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三、技巧 r8xH A
1、1=1,1=2的使用,在SQL语句组合时用的较多 T7,tJk,(
"where 1=1" 是表示选择全部 "where 1=2"全部不选, j_{gk"2:d`
如: 5pDxFs=v
if @strWhere !='' 4uv }6&R
begin MDlCU
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere Wc)^@f[~<
end Uq&|iB#mF
else C>;}CH|X
begin iU3co|q7
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' NO<myN+N
end {S}/LSNB
我们可以直接写成 F[+sc Mx!G
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere IuTTMAt
2、收缩数据库 LvR=uD
--重建索引 55AG>j&41
DBCC REINDEX w#o<qrpHf
DBCC INDEXDEFRAG 0
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--收缩数据和日志 :9)>!+|'
DBCC SHRINKDB 6"wY;E
DBCC SHRINKFILE )~J/,\
3、压缩数据库 &K7g8x"x.
dbcc shrinkdatabase(dbname) Lt*H|9
4、转移数据库给新用户以已存在用户权限 *Vc}W
exec sp_change_users_login 'update_one','newname','oldname' j/W#=\xz
go f(3#5288
5、检查备份集 2Zl65
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' !~RD>N&n
6、修复数据库 bi_R.sfK&
ALTER DATABASE [dvbbs] SET SINGLE_USER J3$ihH.
GO OLiYjYd
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK ;[|x5o/<
GO gcz1*3)
ALTER DATABASE [dvbbs] SET MULTI_USER j;'NJ~NZ$
GO ~r{Nc j
7、日志清除 gh~C.>W}q+
SET NOCOUNT ON s_]rje8`
DECLARE @LogicalFileName sysname, F'"-4YV>&
@MaxMinutes INT, bkY7]'.bz&
@NewSize INT _x:K%1_[
USE tablename -- 要操作的数据库名 ?=\h/C
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 0/%zXp&m
@MaxMinutes = 10, -- Limit on time allowed to wrap log. Ar\`OhR
@NewSize = 1 -- 你想设定的日志文件的大小(M) #3qkG)
-- Setup / initialize IX3r$}4
DECLARE @OriginalSize int gU8'7H2
SELECT @OriginalSize = size &r_:n t
FROM sysfiles 5tf/VT
WHERE name = @LogicalFileName m7eO T
SELECT 'Original Size of ' + db_name() + ' LOG is ' + O[N{&\$
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + Sw0~6RZ
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' m.2
FROM sysfiles %xY'v$
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WHERE name = @LogicalFileName F:\y#U6"J
CREATE TABLE DummyTrans aC:rrS
(DummyColumn char (8000) not null) _{A($/~c?
DECLARE @Counter INT, Fa;CWyt
@StartTime DATETIME, Z(V4"x7F
@TruncLog VARCHAR(255) pIh@!C
SELECT @StartTime = GETDATE(), } wiq?dr
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' >si<VCO
DBCC SHRINKFILE (@LogicalFileName, @NewSize) 2Aff3]-:Gd
EXEC (@TruncLog) <|.M]]}j
-- Wrap the log if necessary. (;s\Ip0
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired r[hfN2,#
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) d29]R.
AND (@OriginalSize * 8 /1024) > @NewSize |#S!qnXB
BEGIN -- Outer loop. f+)F-3
SELECT @Counter = 0 "=qdBG9
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) Q@M,:0+cy
BEGIN -- update `a<G7
INSERT DummyTrans VALUES ('Fill Log') 9m#`56G`
DELETE DummyTrans VJwzYl
SELECT @Counter = @Counter + 1 `]fY9ZDKs
END :@pmgp
EXEC (@TruncLog) Hiw{1E:rW
END OnD+/I
SELECT 'Final Size of ' + db_name() + ' LOG is ' + k1]?d7g$w
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + r*kk/$,2
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' x*_c'\F|
FROM sysfiles )EO$JwQ
WHERE name = @LogicalFileName H
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DROP TABLE DummyTrans JNZKzyJ9K
SET NOCOUNT OFF XX/cJp
8、说明:更改某个表 {gJOc,U4b
exec sp_changeobjectowner 'tablename','dbo' d`2VbZC`
9、存储更改全部表 %T88K}?=
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch C=.
@OldOwner as NVARCHAR(128), bd%/dr
@NewOwner as NVARCHAR(128) h883pe=
AS Qx
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DECLARE @Name as NVARCHAR(128) e#08,wgW
DECLARE @Owner as NVARCHAR(128) yy%J{;
DECLARE @OwnerName as NVARCHAR(128) NjMo"1d
DECLARE curObject CURSOR FOR thkL<
select 'Name' = name, 9g>ay-W[(
'Owner' = user_name(uid) 0C0iAp
from sysobjects PI }A')Nq.
where user_name(uid)=@OldOwner $o-s?";
order by name
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OPEN curObject }J:~}?^%n
FETCH NEXT FROM curObject INTO @Name, @Owner K+n6.BzW
WHILE(@@FETCH_STATUS=0) ;Ni+TS
BEGIN Rh:\/31~
if @Owner=@OldOwner 03#r F@e
begin cA_v*`YL
set @OwnerName = @OldOwner + '.' + rtrim(@Name) Yj;$hV8j(
exec sp_changeobjectowner @OwnerName, @NewOwner cz.-cuD[iD
end Tl 9_Wi
-- select @name,@NewOwner,@OldOwner {Rbc
FETCH NEXT FROM curObject INTO @Name, @Owner Ll&Y_Ry
END <~f/T]E,
close curObject 2<<,aL*
deallocate curObject GT*\gZ
GO .\i9}ye
10、SQL SERVER中直接循环写入数据 y|c]r!A
declare @i int =:5yRP
set @i=1 U+nwLxe'
while @i<30 .(3B}}gB>
begin YMJ?t"
insert into test (userid) values(@i) I2D<~xP~2+
set @i=@i+1 '|Cs!Zl
end Rh~<#"G]
小记存储过程中经常用到的本周,本月,本年函数 w!tQU9+*
Dateadd(wk,datediff(wk,0,getdate()),-1) 5q"
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Dateadd(wk,datediff(wk,0,getdate()),6) 17J|g.]m-&
Dateadd(mm,datediff(mm,0,getdate()),0) o^gqpQv
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) aQkgkV;~
Dateadd(yy,datediff(yy,0,getdate()),0) C
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Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) /G\-v2i D
上面的SQL代码只是一个时间段 H<"{wUPT0
Dateadd(wk,datediff(wk,0,getdate()),-1) :Iw)xd1d}\
Dateadd(wk,datediff(wk,0,getdate()),6) YQ2ie>C8
就是表示本周时间段. m
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下面的SQL的条件部分,就是查询时间段在本周范围内的: =XyK/$
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) fM d]P:B
而在存储过程中 )7:2v1Xr]
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) .}2^YOmd
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) P|c79