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。 ~Lc>~!!t
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一、基础 G=8w9-Ww
1、说明:创建数据库 aqb;H 'F
CREATE DATABASE database-name J9LS6~
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2、说明:删除数据库 I@=h|GM
drop database dbname X'&$wQ6,K
3、说明:备份sql server
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--- 创建 备份数据的 device 3"gifE
USE master )r2$/QF9
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' bmAgB}Ior
--- 开始 备份 sK:,c5^
BACKUP DATABASE pubs TO testBack {I|k@
4、说明:创建新表 xX'Uq_Jv
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) '^l/e: (H3
根据已有的表创建新表: ]k mOX
A:create table tab_new like tab_old (使用旧表创建新表) gkpNT)
B:create table tab_new as select col1,col2... from tab_old definition only wYf=(w\c
5、说明:删除新表 Gc9^Z=
drop table tabname ~^.&nph
6、说明:增加一个列 6,xoxNoPP3
Alter table tabname add column col type g)'tr
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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。 K.2M=Q
7、说明:添加主键: Alter table tabname add primary key(col) %f;(
说明:删除主键: Alter table tabname drop primary key(col) f*~ 4Kv
8、说明:创建索引:create [unique] index idxname on tabname(col....) LoG@(g&)
删除索引:drop index idxname Yi[dS`,d
注:索引是不可更改的,想更改必须删除重新建。 t.pg;#
9、说明:创建视图:create view viewname as select statement Uc0AsUu}?
删除视图:drop view viewname Q:~w;I
10、说明:几个简单的基本的sql语句 @2_s;!K
选择:select * from table1 where 范围 +k"dN^K]D
插入:insert into table1(field1,field2) values(value1,value2) $Yz &x%Lb
删除:delete from table1 where 范围 HHZ!mYr
更新:update table1 set field1=value1 where 范围 kXC.rgal
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! bE>3D#V<
排序:select * from table1 order by field1,field2 [desc] ABV\:u
总数:select count as totalcount from table1 ,l<-*yMD
求和:select sum(field1) as sumvalue from table1 z1+rz%
平均:select avg(field1) as avgvalue from table1 1#qCD["8
最大:select max(field1) as maxvalue from table1 G
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最小:select min(field1) as minvalue from table1 v%<_Mh
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11、说明:几个高级查询运算词 ke>\.|HT}
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A: UNION 运算符 tL+8nTL
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 RQ,(?I*8\
B: EXCEPT 运算符 >`NY[Mn
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 !E_uQ?/w]Z
C: INTERSECT 运算符 z K8#gif@
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 oz5o=gt7
注:使用运算词的几个查询结果行必须是一致的。 LO61J_J<
12、说明:使用外连接 YLd
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A、left outer join: dr6 dK
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 Xy*X4JJh^
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c _ga!TQ:
B:right outer join: b+p!{
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 8VcAtrx_
C:full outer join: W? UCo6<m
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 !T,7
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二、提升 ($(1KE
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) *vAOUqX`x
法一:select * into b from a where 1<>1 g&0GO:F`
法二:select top 0 * into b from a h.=B!wKK
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) uWnS<O
insert into b(a, b, c) select d,e,f from b; ['km'5uZ^
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) Rg[e~##
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 IPxfjBC+J
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. l!AZ$IV
4、说明:子查询(表名1:a 表名2:b) u
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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) gy =`c MS@
5、说明:显示文章、提交人和最后回复时间 ` 4EOy:a
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b Bhq(bV
6、说明:外连接查询(表名1:a 表名2:b) @I"Aet'XV
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c peqFa._W
7、说明:在线视图查询(表名1:a ) H9)uni
select * from (SELECT a,b,c FROM a) T where t.a > 1; ''v1Pv-
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 d7^XP
select * from table1 where time between time1 and time2 *VlYl"
select a,b,c, from table1 where a not between 数值1 and 数值2 hYd8}BvA
9、说明:in 的使用方法 6$6NVq
select * from table1 where a [not] in ('值1','值2','值4','值6') aq5<Ks `r
10、说明:两张关联表,删除主表中已经在副表中没有的信息 E7eVg*Cvi
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) ygfqP
11、说明:四表联查问题: ;5|EpoM
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... &yA<R::o
12、说明:日程安排提前五分钟提醒 (x^|
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 =-VV`
13、说明:一条sql 语句搞定数据库分页 ONGe/CEXT
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 \7j)^
14、说明:前10条记录 kxn;;
select top 10 * form table1 where 范围 *i?qOv/=>
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) `X^e}EGWu
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) YqJIp. Z
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 ^w12k2a
(select a from tableA ) except (select a from tableB) except (select a from tableC) n#&RY%#`
17、说明:随机取出10条数据 Mc}x]j`f
select top 10 * from tablename order by newid() \QMSka>
18、说明:随机选择记录 ?@#}%<yEq
select newid() 'j3'n0o
19、说明:删除重复记录 P~qVr#eU
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) &"kx(B
20、说明:列出数据库里所有的表名 3QHZC0AY
select name from sysobjects where type='U' {PVu3W
21、说明:列出表里的所有的 ]czy8n$+
select name from syscolumns where id=object_id('TableName') )[K3p{4
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。 ibuI/VDF
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 =5|5j!i=q
显示结果: j>b OnCp~
type vender pcs XP` kf]9
电脑 A 1 v4zd
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电脑 A 1 h@DJ/&;u@
光盘 B 2 V0AX1?H~ w
光盘 A 2 !xc7~D@om(
手机 B 3 y^A$bTQq
手机 C 3 QLUe{@ivc
23、说明:初始化表table1 *=7[Ip<X
TRUNCATE TABLE table1 ~/x42|t
24、说明:选择从10到15的记录 /<
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select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc "QF083$
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三、技巧 1%@~J\qF
1、1=1,1=2的使用,在SQL语句组合时用的较多 Qm.kXlsDI
"where 1=1" 是表示选择全部 "where 1=2"全部不选, 0\#Q;Z2
如: @
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if @strWhere !='' `@eH4}L*
begin E nvs[YZe
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere 9>#|~P&FE
end JJ~?ON.H
else _)l %-*Z7p
begin 0hkuBQb\
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' Xdq,
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end >" .qFn g
我们可以直接写成 m%V[&"5%e
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere UH.cn|R
2、收缩数据库 bevT`D
--重建索引 K(d!0S
DBCC REINDEX \$C4H
DBCC INDEXDEFRAG tAA7
--收缩数据和日志 5 q ,
DBCC SHRINKDB ]2(c$R
DBCC SHRINKFILE eFio,
3、压缩数据库 Xu_<4
dbcc shrinkdatabase(dbname) ! -c*lb
4、转移数据库给新用户以已存在用户权限 Ds87#/Yfv
exec sp_change_users_login 'update_one','newname','oldname' rxK0<pWJhx
go (OqJet2{+
5、检查备份集 QC4T=E]`j
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' [j?<9
6、修复数据库 gHx-m2N
ALTER DATABASE [dvbbs] SET SINGLE_USER HUC2RM?FN
GO +I <Sq_-
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK _")h
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GO
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ALTER DATABASE [dvbbs] SET MULTI_USER OD]J@m
GO "AouiZkh
7、日志清除 a+/|O*>#
SET NOCOUNT ON X6.O;
DECLARE @LogicalFileName sysname, :xPvEK[B7
@MaxMinutes INT, w4'K2 7
@NewSize INT qYiAwK$
USE tablename -- 要操作的数据库名 MI(i%$R-A
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 5G!U'.gr
@MaxMinutes = 10, -- Limit on time allowed to wrap log. f4S@lyYF
@NewSize = 1 -- 你想设定的日志文件的大小(M) AE&n^vdQW
-- Setup / initialize GX)QIe~;qJ
DECLARE @OriginalSize int :*@|"4
SELECT @OriginalSize = size *$(CiyF!
FROM sysfiles 9@Sb! 9h
WHERE name = @LogicalFileName %20-^&zZ
SELECT 'Original Size of ' + db_name() + ' LOG is ' + n6G&^Oj
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + v$G*TR<2
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' ;n!X% S<z*
FROM sysfiles F?} *ovy
WHERE name = @LogicalFileName HiG/(<bs9O
CREATE TABLE DummyTrans f hG2
(DummyColumn char (8000) not null) f^4*. ~cB
DECLARE @Counter INT, d5y2Y/QO
@StartTime DATETIME, C[nr>
@TruncLog VARCHAR(255) ~Ls I<z
SELECT @StartTime = GETDATE(), -^H5z+"^
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' ~{YgM/c|dt
DBCC SHRINKFILE (@LogicalFileName, @NewSize) :WIf$P?X
EXEC (@TruncLog) WWcm(q=
-- Wrap the log if necessary. Noxz kpMF
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired &t/<yq}{
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) 9yo[T(8
AND (@OriginalSize * 8 /1024) > @NewSize %"Q!5qH&
BEGIN -- Outer loop. iwJ-<v_:h
SELECT @Counter = 0 hZWK5KwT
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) iFG5%>5F
BEGIN -- update /JeqoM"x
INSERT DummyTrans VALUES ('Fill Log') W<91m*
DELETE DummyTrans &PuJV + y
SELECT @Counter = @Counter + 1 s| r7DdI
END THgzT\_zq
EXEC (@TruncLog) y] ]Vp~R:[
END +Nbk\%
SELECT 'Final Size of ' + db_name() + ' LOG is ' + ff1B)e
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + HoE.//b
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' R9/xC7l@
FROM sysfiles j' KobyX<
WHERE name = @LogicalFileName hS{
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DROP TABLE DummyTrans 8ex:OTzn|
SET NOCOUNT OFF y/I~x+y
8、说明:更改某个表 = )l: ^+q
exec sp_changeobjectowner 'tablename','dbo' "!Oh#Vf
9、存储更改全部表 DUKmwKM"k
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch yr9A0F0
@OldOwner as NVARCHAR(128), |C6(0fgWd
@NewOwner as NVARCHAR(128) ICbdKgLz
AS 0aTbzOn&
DECLARE @Name as NVARCHAR(128) G\N"rG =
DECLARE @Owner as NVARCHAR(128) 7]xz8t
DECLARE @OwnerName as NVARCHAR(128) qm8n7Z/
DECLARE curObject CURSOR FOR C.)&FW2F_
select 'Name' = name, Bb[e[,ah
'Owner' = user_name(uid) gDNTIOV
from sysobjects _K}_h\e.
where user_name(uid)=@OldOwner z!C4>,
order by name G\>\VA
OPEN curObject +.#S[G
FETCH NEXT FROM curObject INTO @Name, @Owner `J#xyDL6?
WHILE(@@FETCH_STATUS=0) l[ ": tG
BEGIN a]Da`$T
if @Owner=@OldOwner uM)9b*Vbo
begin n+\Cw`'<H
set @OwnerName = @OldOwner + '.' + rtrim(@Name) 1X"H6j[w
exec sp_changeobjectowner @OwnerName, @NewOwner ^$+f3Z'
end |@L &yg,x
-- select @name,@NewOwner,@OldOwner *_/eAi/WG
FETCH NEXT FROM curObject INTO @Name, @Owner G'?f!fz;
END 7cmr
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close curObject sJI-
deallocate curObject '"]>`=R
GO 0?Tk* X
10、SQL SERVER中直接循环写入数据 o%^k T&
declare @i int }Q r0T
set @i=1 )-?uX.E{
while @i<30 `-K)K<
begin D*T$ v
insert into test (userid) values(@i) wdcryejCkr
set @i=@i+1 h/0-Mrk;e
end lmtQr5U
小记存储过程中经常用到的本周,本月,本年函数 z@l!\m-
Dateadd(wk,datediff(wk,0,getdate()),-1) C+(Gg^ w
Dateadd(wk,datediff(wk,0,getdate()),6) Z>Kcz^a#
Dateadd(mm,datediff(mm,0,getdate()),0) .)^3t~
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) _/%]:
Dateadd(yy,datediff(yy,0,getdate()),0) ;TV'PJ
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) Z!RRe]"y
上面的SQL代码只是一个时间段 `YmI'
Dateadd(wk,datediff(wk,0,getdate()),-1) Q0q)n=i}]
Dateadd(wk,datediff(wk,0,getdate()),6) )'
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就是表示本周时间段. H&yFSz}6a
下面的SQL的条件部分,就是查询时间段在本周范围内的: ~b$z\|Y
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) xL39>PB
而在存储过程中 OZC/+"\,
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) !w#ru?L{
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) ;sck+FP7w