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。 y<F$@
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一、基础 gb(\c:yg1R
1、说明:创建数据库 v03~=(
CREATE DATABASE database-name dab>@z4
2、说明:删除数据库 C>68$wd>
drop database dbname Op3 IL/
3、说明:备份sql server |ry;'[*
--- 创建 备份数据的 device |0f\>X I
USE master jZv8X5i
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' 8zj09T[
--- 开始 备份 =< CH( 4!
BACKUP DATABASE pubs TO testBack d;#9xD'
4、说明:创建新表 Wc3!aLNx
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) RAE|eTnna
根据已有的表创建新表: Q X@&~
A:create table tab_new like tab_old (使用旧表创建新表) ciC4V^f
B:create table tab_new as select col1,col2... from tab_old definition only qC\$>QU}
5、说明:删除新表 '%RMpyK~
drop table tabname 1rPeh{SZ
6、说明:增加一个列 ^DZiz[X+|
Alter table tabname add column col type g8kw|BgnL
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。 PLLlo~Bb
7、说明:添加主键: Alter table tabname add primary key(col) >4EcV1y
说明:删除主键: Alter table tabname drop primary key(col) flLmZ1"
8、说明:创建索引:create [unique] index idxname on tabname(col....) [RpFC4W
删除索引:drop index idxname p'w[5'
注:索引是不可更改的,想更改必须删除重新建。 cJ8*[H<NV
9、说明:创建视图:create view viewname as select statement xC;$/u%'
删除视图:drop view viewname n;rOH[P
10、说明:几个简单的基本的sql语句 F$ h/k^
选择:select * from table1 where 范围 McsqMI6
插入:insert into table1(field1,field2) values(value1,value2) 95]%j\
删除:delete from table1 where 范围 X<9DE!/)
更新:update table1 set field1=value1 where 范围 VDnAQ[T@d
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! E #ys-t 42
排序:select * from table1 order by field1,field2 [desc] Z<,gSut'Y
总数:select count as totalcount from table1 C)C;U&Qd
求和:select sum(field1) as sumvalue from table1 Kv#daAU
平均:select avg(field1) as avgvalue from table1 aRG[F*BY
最大:select max(field1) as maxvalue from table1
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最小:select min(field1) as minvalue from table1 L<QDC
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11、说明:几个高级查询运算词 >a4Bfnf"eI
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A: UNION 运算符 Rkm7"dO0
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。 19#)#
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B: EXCEPT 运算符 ]ipVN
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。 O_iX1@SW
C: INTERSECT 运算符
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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。 *<0g/AL
注:使用运算词的几个查询结果行必须是一致的。 |d`?wm-
12、说明:使用外连接 b&_p"8)_
A、left outer join: oNCDG|8z
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。 fGe{7p6XV*
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 i'5bPW
B:right outer join: 2Q k\}KWs
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。 (/KF;J^M
C:full outer join: &0C!P=-p
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。 8v6rS-iHP
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二、提升 ^#t<ILUa
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) SQ1&n;M}f
法一:select * into b from a where 1<>1 WI~%n
法二:select top 0 * into b from a #&5\1Qu
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) T ]zjJwa
insert into b(a, b, c) select d,e,f from b; 87>Qw,r
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) qnm9Lw#
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 3}gK`1Nq1
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. ./g#<
4、说明:子查询(表名1:a 表名2:b) h n]6he
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) =lmh^**4
5、说明:显示文章、提交人和最后回复时间 JR>B<{xB
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b .z4FuG,R
6、说明:外连接查询(表名1:a 表名2:b) !*ucVv;
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c )I$Mh@F
7、说明:在线视图查询(表名1:a ) S8cFD):q
select * from (SELECT a,b,c FROM a) T where t.a > 1; He*L"VpWv
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 'Hia6<m3
select * from table1 where time between time1 and time2 a$|u!_)!h
select a,b,c, from table1 where a not between 数值1 and 数值2 :OZhEBL&b
9、说明:in 的使用方法 U{}7:&As
select * from table1 where a [not] in ('值1','值2','值4','值6') Z"^@B2v
10、说明:两张关联表,删除主表中已经在副表中没有的信息 enrmjA&3
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) E<4}mSn)
11、说明:四表联查问题: 1M{#"t{6
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 ..... sI'HS+~pU
12、说明:日程安排提前五分钟提醒 5.E 2fX
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 $G}Q}f
13、说明:一条sql 语句搞定数据库分页 W P&zF$
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 "|%fAE
14、说明:前10条记录 E4.IS=4S
select top 10 * form table1 where 范围 UmuFzw^
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.) fh3
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select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) O^$Zz<
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 gc:>HX);)
(select a from tableA ) except (select a from tableB) except (select a from tableC) syfR5wc
17、说明:随机取出10条数据 qs b4@jt+
select top 10 * from tablename order by newid() >dGYZfqD
18、说明:随机选择记录 j%h
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select newid() .0ZvCv:>
19、说明:删除重复记录 =>J#_Pprn
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) [P,nW/H
20、说明:列出数据库里所有的表名 {ULnQ6@
select name from sysobjects where type='U' ]>,|v,i
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21、说明:列出表里的所有的 ]rm=F]W/n
select name from syscolumns where id=object_id('TableName') # 0(\s@r.
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 }>:X|4]
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type TK>}$.c%+
显示结果: ;v'Y'!-J
type vender pcs OY#_0p)i
电脑 A 1 z~5'p(|@f
电脑 A 1 pp`U]Q5"gX
光盘 B 2 G<eJ0S
光盘 A 2 a+i+#*8wm
手机 B 3 `!8Z"xD
手机 C 3 jY.%~Y1y
23、说明:初始化表table1 e-CW4x
TRUNCATE TABLE table1 zE/(F;> FV
24、说明:选择从10到15的记录 J"MJVMo$T
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc ZIl<y{
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三、技巧 >KFJ1}b|3
1、1=1,1=2的使用,在SQL语句组合时用的较多 "LWuN>
"where 1=1" 是表示选择全部 "where 1=2"全部不选, dp70sA!JF
如: I2T2'_I
if @strWhere !='' k#&SWp=
begin .#J3UZ
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere ( -@>
end 6hq)yUvo4
else ;p ('cwU%
begin S@)bl
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' XEEbmIO*<9
end <hbbFL}|%
我们可以直接写成 U8KY/!XZ
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere [
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2、收缩数据库 SI9hS4<j
--重建索引 ^'4uTbxP_!
DBCC REINDEX h)vTu%J:
DBCC INDEXDEFRAG xn8B|axB
--收缩数据和日志 LH;G:
DBCC SHRINKDB 8|GpfW3p2
DBCC SHRINKFILE WV
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3、压缩数据库 1n"X?K5;A
dbcc shrinkdatabase(dbname) &L]*]Xz;
4、转移数据库给新用户以已存在用户权限 7p$*/5fk
exec sp_change_users_login 'update_one','newname','oldname' #O+]ydvT
go #^ #i]{g
5、检查备份集 ZB&Uhi
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' Rp*t"HSaAW
6、修复数据库 ^nF$<#a
ALTER DATABASE [dvbbs] SET SINGLE_USER jYz3(mM'J
GO %#a%Luq
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK <GRf%zJ
GO 9A(K_d-!H
ALTER DATABASE [dvbbs] SET MULTI_USER +GU16+w~E
GO \k_3IP?o=
7、日志清除 |/;5|
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SET NOCOUNT ON 4?&a?*M
DECLARE @LogicalFileName sysname, M3 u8NRd5|
@MaxMinutes INT, %U7f9
@NewSize INT 4/WCs$
USE tablename -- 要操作的数据库名 QB,ad
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 2v1&%x:y#
@MaxMinutes = 10, -- Limit on time allowed to wrap log. -Wk"o?}q
@NewSize = 1 -- 你想设定的日志文件的大小(M) V2%wb\_z
-- Setup / initialize qEr[fC@x
DECLARE @OriginalSize int
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SELECT @OriginalSize = size =_J<thp
FROM sysfiles j//wh1
WHERE name = @LogicalFileName )du{ZWr
SELECT 'Original Size of ' + db_name() + ' LOG is ' + p9WskYpm
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + vh8Kd' y
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' ]#.&f]6l
FROM sysfiles S(h*\we
WHERE name = @LogicalFileName J)|K/W9
CREATE TABLE DummyTrans _ n4ma
(DummyColumn char (8000) not null) F@bCm+z-
DECLARE @Counter INT, K<JP9t6Qd
@StartTime DATETIME, |qDfFGYf
@TruncLog VARCHAR(255) QvN
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SELECT @StartTime = GETDATE(), L0 2~FT
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' 7=A9E]:
DBCC SHRINKFILE (@LogicalFileName, @NewSize) {Y%=/ba W
EXEC (@TruncLog) F|`B2Gr
-- Wrap the log if necessary. [#'_@zZz
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired NV4W2thYo
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) >%dAqYi $
AND (@OriginalSize * 8 /1024) > @NewSize ibs"Iv34
BEGIN -- Outer loop. no6]{qn=6
SELECT @Counter = 0 jdf)bO(9#
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) <9tG_
BEGIN -- update vXQmEIm
INSERT DummyTrans VALUES ('Fill Log') <#
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DELETE DummyTrans 7h/Q;P5
SELECT @Counter = @Counter + 1 0]W]#X4A
END +STzG/9#
EXEC (@TruncLog) 72vGfT2HtZ
END =e-aZ0P
SELECT 'Final Size of ' + db_name() + ' LOG is ' + x>"JWD
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + TbAdTmW
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' XPo'iI-
FROM sysfiles igj@{FN
WHERE name = @LogicalFileName *"{Z?< 3
DROP TABLE DummyTrans \1C!,C
SET NOCOUNT OFF bk9~63tN+>
8、说明:更改某个表 .hNw1~Fj
exec sp_changeobjectowner 'tablename','dbo'
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9、存储更改全部表 !&jgcw/E
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch jI<WzvhYG
@OldOwner as NVARCHAR(128), |0R%!v(,
@NewOwner as NVARCHAR(128) .x?zky^
AS #n)W
DECLARE @Name as NVARCHAR(128) T KL(97)<
DECLARE @Owner as NVARCHAR(128) [mzF)/[_2
DECLARE @OwnerName as NVARCHAR(128) Le:mMd= G
DECLARE curObject CURSOR FOR qq3Qd,$Z
select 'Name' = name, U]EuDNkO{
'Owner' = user_name(uid) zRE8299%z
from sysobjects UA4d|^ev
where user_name(uid)=@OldOwner ,bp pM
order by name <O)X89dFM
OPEN curObject u4M2Ec
FETCH NEXT FROM curObject INTO @Name, @Owner C{i;spc!bi
WHILE(@@FETCH_STATUS=0) #]a51Vss
BEGIN ~2DV{dyj
if @Owner=@OldOwner FDs^S)B
begin jTUf4&b-
set @OwnerName = @OldOwner + '.' + rtrim(@Name) $RNUr
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exec sp_changeobjectowner @OwnerName, @NewOwner a{Hb7&
end IetGg{h.
-- select @name,@NewOwner,@OldOwner VD&3%G!
FETCH NEXT FROM curObject INTO @Name, @Owner ?[1qC=[Z<
END 15T[J%7f
close curObject 9AddF*B
deallocate curObject )'dH}3Ba
GO
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10、SQL SERVER中直接循环写入数据 )^>XZ*eK
declare @i int t:sq*d
set @i=1 SLjf<.S
while @i<30 7O9hn2?e
begin
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insert into test (userid) values(@i) C
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set @i=@i+1 #Q7x:,f
end "~2#!bK7
小记存储过程中经常用到的本周,本月,本年函数 )Z]y.W )
Dateadd(wk,datediff(wk,0,getdate()),-1) 6?.pKFBZ
Dateadd(wk,datediff(wk,0,getdate()),6) u#@{%kPW
Dateadd(mm,datediff(mm,0,getdate()),0) HGQ?(2] 8$
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) =<zSF\Zr_
Dateadd(yy,datediff(yy,0,getdate()),0) ytV)!xe
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) D<3V#Opw
上面的SQL代码只是一个时间段 l8AEEG8>
Dateadd(wk,datediff(wk,0,getdate()),-1) ZIL|
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Dateadd(wk,datediff(wk,0,getdate()),6) n$|c{2]=
就是表示本周时间段. z vb}p
下面的SQL的条件部分,就是查询时间段在本周范围内的: 9C)3
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Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) /b:t;0G
而在存储过程中 i Kk"j
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) =Pb5b6Y@6
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) 5-WRv;