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。 to\Ni~a&
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一、基础 rbQR,Nf2x
1、说明:创建数据库 <1pEwI~
CREATE DATABASE database-name }i2V.tVB-
2、说明:删除数据库 Ha ]YJ}
drop database dbname 5?L<N:;J_
3、说明:备份sql server KU;9}!#
--- 创建 备份数据的 device Q &t<Y^B
USE master xCKRxF
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' 0g\(+Qg^
--- 开始 备份 WKU=.sY
BACKUP DATABASE pubs TO testBack SB7c.H,
4、说明:创建新表 >Se,;cB'/]
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) [:V$y1
根据已有的表创建新表: %UM
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A:create table tab_new like tab_old (使用旧表创建新表) 8X0z~&
B:create table tab_new as select col1,col2... from tab_old definition only 5PW^j\G-f
5、说明:删除新表 rGkyGz8>
drop table tabname c)tfAD(N8x
6、说明:增加一个列 uGt-l4
Alter table tabname add column col type <,(,jU)j
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。 KYP!Rs/j.
7、说明:添加主键: Alter table tabname add primary key(col) d %#b:(,
说明:删除主键: Alter table tabname drop primary key(col) c"Sq~X
8、说明:创建索引:create [unique] index idxname on tabname(col....) p:%loDk
删除索引:drop index idxname fzA9'i`
注:索引是不可更改的,想更改必须删除重新建。 X jX2]
9、说明:创建视图:create view viewname as select statement xKC[=E>z
删除视图:drop view viewname yEoV[K8k
10、说明:几个简单的基本的sql语句 qCO/?kW
选择:select * from table1 where 范围 0;ji65
插入:insert into table1(field1,field2) values(value1,value2) C-[1iW'
删除:delete from table1 where 范围 g1o8._f.
更新:update table1 set field1=value1 where 范围 3,=6@U
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! $g7<Y*t[
排序:select * from table1 order by field1,field2 [desc] !a<ng&H^U
总数:select count as totalcount from table1 N[yy M'C
求和:select sum(field1) as sumvalue from table1 G9:l'\
平均:select avg(field1) as avgvalue from table1 V>
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最大:select max(field1) as maxvalue from table1 K@#L)VT!
最小:select min(field1) as minvalue from table1 :@)>r9N
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11、说明:几个高级查询运算词 `@
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A: UNION 运算符 s0_nLbWwO
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 U?=Dg1
B: EXCEPT 运算符 9E tz[`|
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 -]=@s
C: INTERSECT 运算符 e]tDy0@
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 h@h! ,;
注:使用运算词的几个查询结果行必须是一致的。 2Gdd*=4z
12、说明:使用外连接 RGU\h[
A、left outer join: r4f~z$QK
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。 5Dl/aHb
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 CA#,THty
B:right outer join: nvUc\7(%NW
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。 WT}H>T
C:full outer join: H4JTGt1"
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。 l (%1jC8
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二、提升 F3N6{ysK#
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) T n}s*<=V
法一:select * into b from a where 1<>1 e!r-+.i(
法二:select top 0 * into b from a AvHCO8h|
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) @gtQQxf"
insert into b(a, b, c) select d,e,f from b; ^BL"wk
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) 2>H24F
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 5 BJmA2L
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. e,5C8Q`Z
4、说明:子查询(表名1:a 表名2:b) {>%&(
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) ~WN:DXn
5、说明:显示文章、提交人和最后回复时间 Ydy9
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b -)/$M(Pu"
6、说明:外连接查询(表名1:a 表名2:b) XS BA$y
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c N"y)Oca{
7、说明:在线视图查询(表名1:a ) _{Hj^}+$
select * from (SELECT a,b,c FROM a) T where t.a > 1; *~H Sy8s
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 Y)a^(!<H<
select * from table1 where time between time1 and time2 evJ.<{M
select a,b,c, from table1 where a not between 数值1 and 数值2 pXK^Y'2C!
9、说明:in 的使用方法 &yol_%C
select * from table1 where a [not] in ('值1','值2','值4','值6') vI)LB)Q
10、说明:两张关联表,删除主表中已经在副表中没有的信息 C{bgkzr
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) ,'iE;o{Tu
11、说明:四表联查问题:
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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 ..... 8'r[te4,
12、说明:日程安排提前五分钟提醒 .-X8J t
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 :U(A;U1,
13、说明:一条sql 语句搞定数据库分页 ;]jNk'oa
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 K}U-w:{
14、说明:前10条记录 WSY}d
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select top 10 * form table1 where 范围 PAOJ\U
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.) SC])?h-Fw
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) zZC9\V}R
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 V,?yPi$#E
(select a from tableA ) except (select a from tableB) except (select a from tableC) -FlzEZ
17、说明:随机取出10条数据 ED&
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select top 10 * from tablename order by newid() /Qk4
18、说明:随机选择记录 kn"(A.R
select newid() f0aKlhEC
19、说明:删除重复记录 -\n@%$M]G
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) 'oC)
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20、说明:列出数据库里所有的表名 _H=Uwi_g
select name from sysobjects where type='U' ~BkCp pI
21、说明:列出表里的所有的 g
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select name from syscolumns where id=object_id('TableName') U~l$\c
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 BIWWMg
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type P_p<`sC9
显示结果: )D82N`c2\i
type vender pcs .%C|+#&d
电脑 A 1 #`X?=/q
电脑 A 1 ApXy=?fc
光盘 B 2 :Qf '2.h)
光盘 A 2 f.`*Qg L
手机 B 3 78%~N`x7
手机 C 3 V}NbuvDB@
23、说明:初始化表table1 1|6%evPu(
TRUNCATE TABLE table1 Sa`Xf\
24、说明:选择从10到15的记录 v2;`f+
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc 9v!1V,`j"
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三、技巧 1q1jZqno
1、1=1,1=2的使用,在SQL语句组合时用的较多 \A6B,|@
"where 1=1" 是表示选择全部 "where 1=2"全部不选, fLm*1S|%\
如: |WdPE@P
if @strWhere !='' \`\ZTZni
begin B i<Q=x'Z;
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere hzbw>g+
end JOim3(5?s
else A:9?ZI/X
begin x*&|0n.D
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' Ziu]'#
end B|AV$N*
我们可以直接写成 RTJ3qhY
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere fCobzDy
2、收缩数据库 eSmLf*\G
--重建索引 fG w9!
DBCC REINDEX ""QP%
DBCC INDEXDEFRAG 'xg
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--收缩数据和日志 x6ARzH\
DBCC SHRINKDB 1!T1Y,w
DBCC SHRINKFILE =-lb)Z"d
3、压缩数据库 {9aE5kR
dbcc shrinkdatabase(dbname) "djw>|,N<
4、转移数据库给新用户以已存在用户权限 pK'V9fD5J
exec sp_change_users_login 'update_one','newname','oldname' #7YY<)
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go (%W&4a1di
5、检查备份集 ^7KH _t8
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' M8b;d}XL
6、修复数据库 dIBE!4 V[
ALTER DATABASE [dvbbs] SET SINGLE_USER ?r 2` Q
GO LRG6:&
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK &wE%<"aRAl
GO fG(SNNl+D
ALTER DATABASE [dvbbs] SET MULTI_USER TNh1hhJ$b
GO #PQB(=299P
7、日志清除 8j\cL'
SET NOCOUNT ON \:ak ''
DECLARE @LogicalFileName sysname, r|PB*`
@MaxMinutes INT, '9j="R;
@NewSize INT 7 uKY24
USE tablename -- 要操作的数据库名 6N
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SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 &,CiM0
@MaxMinutes = 10, -- Limit on time allowed to wrap log. P8)=Kbd
@NewSize = 1 -- 你想设定的日志文件的大小(M) j*jo@N|
-- Setup / initialize }\:NuTf
DECLARE @OriginalSize int "#oHYz3D
SELECT @OriginalSize = size zZ323pq
FROM sysfiles YCM]VDx4u1
WHERE name = @LogicalFileName ]cMqahaY
SELECT 'Original Size of ' + db_name() + ' LOG is ' + f-n1I^|
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + *8_wYYH
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' R1GEh&U{
FROM sysfiles 4X
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WHERE name = @LogicalFileName | Aw%zw1@
CREATE TABLE DummyTrans
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(DummyColumn char (8000) not null) t+iHQfuP9A
DECLARE @Counter INT, 9!}8UALD
@StartTime DATETIME, $!yW_HTx
@TruncLog VARCHAR(255) 1@1U/ss1
SELECT @StartTime = GETDATE(), ^R
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@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' 0dhaAq`k
DBCC SHRINKFILE (@LogicalFileName, @NewSize) #(JNn'fzq
EXEC (@TruncLog) 4 k _vdz
-- Wrap the log if necessary. 5ZK@`jkE
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired c~uKsU
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) Vq?p|wy
AND (@OriginalSize * 8 /1024) > @NewSize ,+xB$e
BEGIN -- Outer loop. >X4u]>X
SELECT @Counter = 0 F!Q@u
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) '*w00
BEGIN -- update CtAwBQO
INSERT DummyTrans VALUES ('Fill Log') [knN:{ l
DELETE DummyTrans r^paD2&}
SELECT @Counter = @Counter + 1 /%TI??PGu
END =U|.^5sa#
EXEC (@TruncLog) VAf1 " )pC
END ;he"ph=>
SELECT 'Final Size of ' + db_name() + ' LOG is ' + z'\_jaj^
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + Slher0.Y
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' \BZhf?9U
FROM sysfiles SY^t} A7:/
WHERE name = @LogicalFileName 7KL v6]b
DROP TABLE DummyTrans kDN:ep{/
SET NOCOUNT OFF ]?
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8、说明:更改某个表 ?_vakJ
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exec sp_changeobjectowner 'tablename','dbo' 2Yn <2U/^R
9、存储更改全部表 $?<Z!*x
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch .=;3d~.]
@OldOwner as NVARCHAR(128), tlqiXh<
@NewOwner as NVARCHAR(128) -~30)J=e`
AS NzSoqh{R
DECLARE @Name as NVARCHAR(128) N<|Nwq:NN
DECLARE @Owner as NVARCHAR(128) 5^lxj~ F
DECLARE @OwnerName as NVARCHAR(128) V7P&%oz{C
DECLARE curObject CURSOR FOR au=o6WRa
select 'Name' = name, Hx*;jpy(2
'Owner' = user_name(uid) W7\f1}]H
from sysobjects }w<7.I
where user_name(uid)=@OldOwner S.m{eur!,E
order by name CcFn.omA
OPEN curObject 3.W@ }
FETCH NEXT FROM curObject INTO @Name, @Owner X+S9{X#Cm
WHILE(@@FETCH_STATUS=0) O_DtvjI'
BEGIN 6%Pdy$ P
if @Owner=@OldOwner "C19b:4H
begin |J}Mgb-4
set @OwnerName = @OldOwner + '.' + rtrim(@Name)
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exec sp_changeobjectowner @OwnerName, @NewOwner WP+oFkw>
end R0vI bFwj
-- select @name,@NewOwner,@OldOwner 4K\(xd&Q
FETCH NEXT FROM curObject INTO @Name, @Owner ws|;`
END L>%o[tS
close curObject e5B Qr$j
deallocate curObject m{uxIza
GO )3w@]5j
10、SQL SERVER中直接循环写入数据 % !>I*H
declare @i int #+5pgD2C
set @i=1 aL%AQB,
while @i<30 muZ~*kMc
begin DRgTe&+
insert into test (userid) values(@i) ul2")HL];
set @i=@i+1 CS-uNG6
end ayD}r#7
小记存储过程中经常用到的本周,本月,本年函数 pxf$1
Dateadd(wk,datediff(wk,0,getdate()),-1) k
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Dateadd(wk,datediff(wk,0,getdate()),6) i Ae<&Ms
Dateadd(mm,datediff(mm,0,getdate()),0) hn=[1<#^(
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) ?zVL;gVWA
Dateadd(yy,datediff(yy,0,getdate()),0) ;Q[mL(1:
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) [4C:r!
上面的SQL代码只是一个时间段 [uls8
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Dateadd(wk,datediff(wk,0,getdate()),-1) u1PaHgi$
Dateadd(wk,datediff(wk,0,getdate()),6) ,%Up0Rr,
就是表示本周时间段. &PK\|\\2
下面的SQL的条件部分,就是查询时间段在本周范围内的: Q|L9gz[?
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) rJ{O(n]j
而在存储过程中 ,JN8f]a^"g
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) )ZqJh
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) #w-xBM
@