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。 .+yW%~0
EMlIxpCn:
/b#q*x-b
一、基础 HzvlF0f
1、说明:创建数据库 d&jjWlHgEN
CREATE DATABASE database-name BwxnDe G)
2、说明:删除数据库 _A 2Lv]vfV
drop database dbname V^n0GJNo
3、说明:备份sql server JrDHRIkgm
--- 创建 备份数据的 device B3mS]
USE master Uk,g> LG
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' LkBZlh_
--- 开始 备份 #~k[ 6YR 0
BACKUP DATABASE pubs TO testBack >)Gd:636+
4、说明:创建新表 +`.,| |Mq
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) F;u_7OM
根据已有的表创建新表: x=]S.XI
A:create table tab_new like tab_old (使用旧表创建新表) -U-P}6^
B:create table tab_new as select col1,col2... from tab_old definition only 5M:D?9E+
5、说明:删除新表 5ZK&fKeCF
drop table tabname d~@q%-`lA
6、说明:增加一个列 Zu21L3
Alter table tabname add column col type s+,&|;Q
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。 -7%X]
7、说明:添加主键: Alter table tabname add primary key(col) ^ve14mbF#.
说明:删除主键: Alter table tabname drop primary key(col) %d;<2b0
8、说明:创建索引:create [unique] index idxname on tabname(col....) tnb$sulc+
删除索引:drop index idxname .9h)bf+
注:索引是不可更改的,想更改必须删除重新建。 *Qkc[XHqy
9、说明:创建视图:create view viewname as select statement =eBmBn
删除视图:drop view viewname 3b!,D
10、说明:几个简单的基本的sql语句 gnLn7?
选择:select * from table1 where 范围 40#9]=;}
插入:insert into table1(field1,field2) values(value1,value2) SEM8`lnu
删除:delete from table1 where 范围 C\Vg{&'
更新:update table1 set field1=value1 where 范围 [2
zt ^
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! 6~8F!b2
排序:select * from table1 order by field1,field2 [desc] eLfvMPVo
总数:select count as totalcount from table1 nt ,7u(
求和:select sum(field1) as sumvalue from table1 *1^$.Q&
平均:select avg(field1) as avgvalue from table1 cp6WMHLj
最大:select max(field1) as maxvalue from table1 >72JV;W]
最小:select min(field1) as minvalue from table1 30Drrno7Io
r:&|vP
xAhxD|4_
sJZ!sznn
11、说明:几个高级查询运算词 8TWTbQ
WVX`<
Qi9-z'
A: UNION 运算符 E0 l_--
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。 Y3',"
B: EXCEPT 运算符 qZk:mlYd
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。 rmd;\)#*`
C: INTERSECT 运算符 P)6lu8zQ
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。 t6lE#<xZV;
注:使用运算词的几个查询结果行必须是一致的。 n~g LPHY
12、说明:使用外连接 Vz%OV}\
A、left outer join: \9:wfLF8!
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。 ,gx)w^WTm
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 3[IJhR[
B:right outer join: #0"~G][#
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。 Gy"%R-j7
C:full outer join: UBZ9A
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。 >#(n"RCHf
g|%L"-%gJ
C#Bz>2;#
二、提升 UiQEJXwnz
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) nJZ6?
V
法一:select * into b from a where 1<>1 nFM@@oA
法二:select top 0 * into b from a Ne6}oQy(S`
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) 60}! LmL
insert into b(a, b, c) select d,e,f from b; 9$1)k;ChP/
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) / T
c=
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 |/`%3'4H
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. b]Z@^<_E
4、说明:子查询(表名1:a 表名2:b) aFj.i8+
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) 4n0xE[-
5、说明:显示文章、提交人和最后回复时间 ?jO 5 9n
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b <l,o&p,>|c
6、说明:外连接查询(表名1:a 表名2:b) u0o'K9.r
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c w?y6nTg<
7、说明:在线视图查询(表名1:a ) xJwG=$o
select * from (SELECT a,b,c FROM a) T where t.a > 1; K'5'}Lb5k
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 G64Fx*`
select * from table1 where time between time1 and time2 Ykqyk')wm
select a,b,c, from table1 where a not between 数值1 and 数值2 bzZ>lyH
9、说明:in 的使用方法 y$W|~ H
select * from table1 where a [not] in ('值1','值2','值4','值6')
V@vU"
10、说明:两张关联表,删除主表中已经在副表中没有的信息 )3A{GZj#6
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) Y&.UIosWb
11、说明:四表联查问题: {b)~V3rsY
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... ZcE_f>KV
12、说明:日程安排提前五分钟提醒 Vb|#MNf)
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 ZC0-wr\
13、说明:一条sql 语句搞定数据库分页 :aAEJ
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 `#mK*Buem}
14、说明:前10条记录 oG oK,
select top 10 * form table1 where 范围 FMw&(
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) '0RwO[A#1
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) G"SBYU
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表
_D,
;MB&7
(select a from tableA ) except (select a from tableB) except (select a from tableC) NjuiD].
17、说明:随机取出10条数据 R^#@lI~
select top 10 * from tablename order by newid() tt_o$D~kg
18、说明:随机选择记录 SA"p\}"
select newid() M8&}j
19、说明:删除重复记录 MCTsi:V>+
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) 'lz"2@4{
20、说明:列出数据库里所有的表名 kOL'|GgK
select name from sysobjects where type='U' DKL@wr}8
21、说明:列出表里的所有的 lUOvm\
select name from syscolumns where id=object_id('TableName') Qdk6Qubi!
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。 v`PY>c6~
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 *Zk>2<^R
显示结果: &a0r%L()X
type vender pcs 5z}w}zdg
电脑 A 1 23F/\2MSG
电脑 A 1 u.XQ&
光盘 B 2 p=Q0!!_r
光盘 A 2 7- d.ZG
手机 B 3 wK_]/Q-L
手机 C 3 (!L5-8O
23、说明:初始化表table1 `)iY}Iu
TRUNCATE TABLE table1 &[Xu!LP
24、说明:选择从10到15的记录 4,Ic}CvM
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc \nNXxTxX!
dihjpI_
}yn0IWVa
kRJ4-n^@><
三、技巧 g=L]S-e
1、1=1,1=2的使用,在SQL语句组合时用的较多 56lCwXCgA
"where 1=1" 是表示选择全部 "where 1=2"全部不选, DOS0;^f
如: 0|4%4Mt
if @strWhere !='' hwYQGtjF
begin LW6ZAETyL
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere y9H%
Xl
end f|7\DeY9U
else #N(= 3Cj
begin 4*n#yVb/
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' +n0r0:z0
end c_grPk2O4
我们可以直接写成 796\jf$
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere HSUI${<
2、收缩数据库 0oZsb\
--重建索引 p9!"O
DBCC REINDEX Jzji&A~
DBCC INDEXDEFRAG Rd
\.:u
--收缩数据和日志 c,MOv7{x_
DBCC SHRINKDB ~/pzxo$
DBCC SHRINKFILE 'NjzgZ~]P
3、压缩数据库 ?Ea;J0V
dbcc shrinkdatabase(dbname) ^FmU_Q0
4、转移数据库给新用户以已存在用户权限 >eQr<-8
exec sp_change_users_login 'update_one','newname','oldname' 7"F*u :
go #AkV/1Y
5、检查备份集 Y_&g="`Q
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' !l?.5Pm])
6、修复数据库 F_iXd/
ALTER DATABASE [dvbbs] SET SINGLE_USER -&x2&WE'
GO GE;e]Jkjn
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK rEhX/(n#
GO Xaz o9J
ALTER DATABASE [dvbbs] SET MULTI_USER \J. .*,'
GO 9_s6l
7、日志清除 :o-,SrORM
SET NOCOUNT ON E:sz$\Ht)
DECLARE @LogicalFileName sysname, {N2g8W:
@MaxMinutes INT, RoA?p;]<
@NewSize INT W:,4 :|3
USE tablename -- 要操作的数据库名 9O`
m,t
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 6fH@wQ"wN
@MaxMinutes = 10, -- Limit on time allowed to wrap log. q\Q{sv_
@NewSize = 1 -- 你想设定的日志文件的大小(M) TNCgaTJ{h
-- Setup / initialize #4MBoN(3
DECLARE @OriginalSize int <9E0iz+j
SELECT @OriginalSize = size ptatzp]c#
FROM sysfiles O<PO^pi
WHERE name = @LogicalFileName 6vuq1
SELECT 'Original Size of ' + db_name() + ' LOG is ' + lt^\
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + LZJA4?C
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' Ee)[\Qjn
FROM sysfiles Ds#/
WHERE name = @LogicalFileName kIw`P[
CREATE TABLE DummyTrans E#J';tUQ
(DummyColumn char (8000) not null) Wt)Drv{@ {
DECLARE @Counter INT, ;AR{@Fu.
@StartTime DATETIME, #/"8F O%~p
@TruncLog VARCHAR(255) WV3|?,y]qm
SELECT @StartTime = GETDATE(), W>r#RXmh
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' ?]fF3 SJk
DBCC SHRINKFILE (@LogicalFileName, @NewSize) hT$~ygQ
EXEC (@TruncLog) qPB8O1fyU
-- Wrap the log if necessary. H9h@ sSg
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired IEKU-k7}Z
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) !TZhQiorC
AND (@OriginalSize * 8 /1024) > @NewSize C{sLz9
BEGIN -- Outer loop. S(S#
SELECT @Counter = 0 xq-17HKs
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) 7^wc)E^H
BEGIN -- update :tIC~GG]_)
INSERT DummyTrans VALUES ('Fill Log') IDkWGh
DELETE DummyTrans *n]7
SELECT @Counter = @Counter + 1 2LrJ>Mi
END ~$'\L
EXEC (@TruncLog) \!(
END 'O5'i\uz
SELECT 'Final Size of ' + db_name() + ' LOG is ' + ZX ?yL>4
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + D3|oOOoG
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' QM3,'?ekRH
FROM sysfiles 0TfS=scT
WHERE name = @LogicalFileName tz#gClo
DROP TABLE DummyTrans 4h@Z/G!T3
SET NOCOUNT OFF /9o!*K
8、说明:更改某个表 JnHo 9K2.
exec sp_changeobjectowner 'tablename','dbo' !d<"nx[2`
9、存储更改全部表 {x'GJtpb
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch V.os
@OldOwner as NVARCHAR(128), -.g|l\
@NewOwner as NVARCHAR(128) NCxqh <
AS 9lB]~,z
DECLARE @Name as NVARCHAR(128) T\Uek-(
DECLARE @Owner as NVARCHAR(128) iXyO(w4D
DECLARE @OwnerName as NVARCHAR(128) F+ E|r6'i
DECLARE curObject CURSOR FOR *f,DhT/P
select 'Name' = name, iX0iRC6f
'Owner' = user_name(uid) u6`=x$&
from sysobjects #cj6{%c4
where user_name(uid)=@OldOwner fc/ &X
order by name MCU_Z[N#10
OPEN curObject *~m+Nc`D,N
FETCH NEXT FROM curObject INTO @Name, @Owner 8ElKD{.BU8
WHILE(@@FETCH_STATUS=0) \Mg`(,kwe
BEGIN [tMZ G%h
if @Owner=@OldOwner Bo<>e~6P
begin R!l:O=[<
set @OwnerName = @OldOwner + '.' + rtrim(@Name) XU+<?%u}z
exec sp_changeobjectowner @OwnerName, @NewOwner vG \a1H
end Pnd`=%w%]
-- select @name,@NewOwner,@OldOwner ;<UW A.
FETCH NEXT FROM curObject INTO @Name, @Owner `ptj?6N-
END Vy_2 .
close curObject gM [w1^lj
deallocate curObject gN)c
GO ;raN
10、SQL SERVER中直接循环写入数据 B||;'
declare @i int .VTy[|o
set @i=1 "V&+7"Q
while @i<30 W8lx~:v
begin 5,)Qw
insert into test (userid) values(@i) =)hVn
set @i=@i+1 p7:{^
end O?<&+(uMTT
小记存储过程中经常用到的本周,本月,本年函数 _EF&A-kX|u
Dateadd(wk,datediff(wk,0,getdate()),-1) Oy 2+b1{
Dateadd(wk,datediff(wk,0,getdate()),6) w.&1%X(k
Dateadd(mm,datediff(mm,0,getdate()),0) '#(v=|J
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) 4t)%<4
Dateadd(yy,datediff(yy,0,getdate()),0)
aR,}W\6M
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) TYI7<-Mp:[
上面的SQL代码只是一个时间段 }K8/-d6
Dateadd(wk,datediff(wk,0,getdate()),-1) wvrrMGU)a
Dateadd(wk,datediff(wk,0,getdate()),6) 7\ nf:.
就是表示本周时间段. JHf
下面的SQL的条件部分,就是查询时间段在本周范围内的: *D'$"@w3
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) 4%1D}9hO6
而在存储过程中 rQ=,y>-*
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) l4TpH|k
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) 'ejvH;V3i