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。 JOJ?.H&su
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一、基础 NHL{.8L{
1、说明:创建数据库 ['rqz1DL5
CREATE DATABASE database-name y #Xq@
2、说明:删除数据库 -964#>n[
drop database dbname GS4
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3、说明:备份sql server ce\ F~8y
--- 创建 备份数据的 device -l`1j6
USE master f*^)0Po
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' , *A',
--- 开始 备份 P2;I0 !
BACKUP DATABASE pubs TO testBack R)?zL;,x
4、说明:创建新表 Y l1sAf/
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) D#n^U
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根据已有的表创建新表: 1Q ^YaHzuW
A:create table tab_new like tab_old (使用旧表创建新表) yPqZ ,
B:create table tab_new as select col1,col2... from tab_old definition only aj<=]=hr
5、说明:删除新表 NuqWezJm&
drop table tabname ` 'y[i
6、说明:增加一个列 ;/8oP ;X2
Alter table tabname add column col type $}G03G@
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。 }{Ncww!iN
7、说明:添加主键: Alter table tabname add primary key(col) HrZ\=1RB
说明:删除主键: Alter table tabname drop primary key(col) #}rv)
8、说明:创建索引:create [unique] index idxname on tabname(col....) Q@-7{3
删除索引:drop index idxname c~+;P(>
注:索引是不可更改的,想更改必须删除重新建。 U,4:yc,)s
9、说明:创建视图:create view viewname as select statement a}+7MEUmZ/
删除视图:drop view viewname 6T5nr
10、说明:几个简单的基本的sql语句 Cq,ox'kGl
选择:select * from table1 where 范围 YdK]%%
插入:insert into table1(field1,field2) values(value1,value2) R~],5_|
删除:delete from table1 where 范围 3./4] _p
更新:update table1 set field1=value1 where 范围 RrDNEwAr
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! zp2IpYQ,3
排序:select * from table1 order by field1,field2 [desc] !`G7X
总数:select count as totalcount from table1 |NcfR"[c
求和:select sum(field1) as sumvalue from table1 Y(4#b`k3
平均:select avg(field1) as avgvalue from table1 D{aN_0mT
最大:select max(field1) as maxvalue from table1 IP` ;hC
最小:select min(field1) as minvalue from table1 `_6!nkq8
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11、说明:几个高级查询运算词 nKJJ7 RL
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A: UNION 运算符 n(gw%w+\7
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。 0vs9# <&V
B: EXCEPT 运算符 Zq--m/
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。 Ny>tJ~I
C: INTERSECT 运算符 4 }l,F
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。 I T)rhi:
注:使用运算词的几个查询结果行必须是一致的。 i[~oMwc&
12、说明:使用外连接 b0CtQe
A、left outer join: zhDmZ
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。 hY.zwotH
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 |-hzvuSX
B:right outer join: #KonVM(`
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。 rlvo&(a
C:full outer join: T6|zT}cb
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。 O7shY4 Sr
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二、提升 BC0T[o(f8
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) N4%q-fi
法一:select * into b from a where 1<>1 f!~gfnn
法二:select top 0 * into b from a .Z}ySd:X
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) h'x|yy]@3
insert into b(a, b, c) select d,e,f from b; Ch`XwLY9
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) )~<8j
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 .,pGW8Js
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. >ln% 3=
4、说明:子查询(表名1:a 表名2:b) 9d4PH
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) dlC)&Ai
5、说明:显示文章、提交人和最后回复时间 )g:\N8AZK
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b ;$G.?r
6、说明:外连接查询(表名1:a 表名2:b) Ctxs]S tU%
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c WlF"[mU-
7、说明:在线视图查询(表名1:a ) M$z.S0"
select * from (SELECT a,b,c FROM a) T where t.a > 1;
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8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 F7`3,SzHp
select * from table1 where time between time1 and time2 Gw*n,*pz
select a,b,c, from table1 where a not between 数值1 and 数值2 :0.Z/s -
9、说明:in 的使用方法 adh=Kp e!w
select * from table1 where a [not] in ('值1','值2','值4','值6') u0^:
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10、说明:两张关联表,删除主表中已经在副表中没有的信息 E0^~i:Mk
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) *r)/.rK_
11、说明:四表联查问题: _](vt,|L
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... D L_{q6ZK
12、说明:日程安排提前五分钟提醒 M SU|T
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 Vh:%e24Z
13、说明:一条sql 语句搞定数据库分页 \cdNyVY
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 AHP_B&s,Qe
14、说明:前10条记录 lkK+Fm
select top 10 * form table1 where 范围 mu2r#I
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) oQ= Q}
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) KAm v7
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 1e*+k$-{
(select a from tableA ) except (select a from tableB) except (select a from tableC) nsqs*$
17、说明:随机取出10条数据 N.C<Mo
select top 10 * from tablename order by newid() zR/d:P?
18、说明:随机选择记录 >C~-*M9
select newid() D*Y4B?,
19、说明:删除重复记录 mHo}, |
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) ^ad
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20、说明:列出数据库里所有的表名 g]R }w@nJ
select name from sysobjects where type='U' M-u:8dPu
21、说明:列出表里的所有的 <k'=_mC_
select name from syscolumns where id=object_id('TableName') [rv"tz=
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。 _*1/4^
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 w{Wz^=';
显示结果: /E/J<
type vender pcs a&~d,vC
电脑 A 1 T9\wkb.
电脑 A 1 \X5{>nNh
光盘 B 2 @@7<L
光盘 A 2 TmG$Cjf84
手机 B 3 ua*k{0[
手机 C 3 AoL4#.r3H
23、说明:初始化表table1 o&1ewE(O]
TRUNCATE TABLE table1 '$W@I
24、说明:选择从10到15的记录 s)#FqB8
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc Qwb=N
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三、技巧 Mxn>WCPo
1、1=1,1=2的使用,在SQL语句组合时用的较多 d6-a\]gF
"where 1=1" 是表示选择全部 "where 1=2"全部不选, ahA21W`k
如: Zf |%t
if @strWhere !='' |BnjT*_9
begin s_-G`xT>{
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere $*^Ms>Pa_
end v!T%xUb0
else V&<vRIsN
begin ^$SI5WK&)
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' 3'6%P_S
end Y 9]
我们可以直接写成 ~U#afGH$
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere AzVON#rj
2、收缩数据库 k DS
--重建索引 >S3iP?V7
DBCC REINDEX 9S@PY_ms
DBCC INDEXDEFRAG 6Yebc_, R
--收缩数据和日志 eKNZ?!c=
DBCC SHRINKDB :}0y[qc3
DBCC SHRINKFILE jKZJ0`06q
3、压缩数据库 "tB"C6b
dbcc shrinkdatabase(dbname) BB5(=n+
4、转移数据库给新用户以已存在用户权限 .t''(0_kC
exec sp_change_users_login 'update_one','newname','oldname' `;4P?!WG
go Ro$'|}(+A
5、检查备份集 e.jrX;;$!&
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' .w\AyXp
6、修复数据库 +0\BI<aG
ALTER DATABASE [dvbbs] SET SINGLE_USER ]7n+|@3x
GO 2`I"
QU
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK 5*u0VabC<
GO 2Jl6Xc8
ALTER DATABASE [dvbbs] SET MULTI_USER x?Doe`/6?
GO [ !/u,
7、日志清除 4%1sOnl
SET NOCOUNT ON hIu;\dfwk
DECLARE @LogicalFileName sysname, 0P^RciC f
@MaxMinutes INT, (:Rj:8{
@NewSize INT AJt*48H*G
USE tablename -- 要操作的数据库名 :@{(^}N8u
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 ED&>~~k)
@MaxMinutes = 10, -- Limit on time allowed to wrap log. t7tX<|aN
@NewSize = 1 -- 你想设定的日志文件的大小(M) |u8IQR'B
-- Setup / initialize X&fM36o7
DECLARE @OriginalSize int Hj't.lg+j
SELECT @OriginalSize = size wl H6
FROM sysfiles z[X>>P3<n
WHERE name = @LogicalFileName $L_-U~^
SELECT 'Original Size of ' + db_name() + ' LOG is ' + 1@sy:{
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CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + ]3]I`e{
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' V
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FROM sysfiles 3maiBAOKz
WHERE name = @LogicalFileName UXwnE@`F
CREATE TABLE DummyTrans i1$ $86
(DummyColumn char (8000) not null) G=Hvh=K(
DECLARE @Counter INT, OAO|HH
@StartTime DATETIME, @igr~hJ
@TruncLog VARCHAR(255) .Nz2K[
SELECT @StartTime = GETDATE(), fVx<f.xuW
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' :["iBrFp
DBCC SHRINKFILE (@LogicalFileName, @NewSize) |l)SX\Qf`@
EXEC (@TruncLog) _SdO}AiG
-- Wrap the log if necessary. [E<NEl*
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired =V~pQbZ
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) 6U5L>sQ
AND (@OriginalSize * 8 /1024) > @NewSize RhR{EO
BEGIN -- Outer loop. PNY"Lqj
SELECT @Counter = 0 V:HxRMF2X
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) @ -CZa^g
BEGIN -- update |N, KA|Gdq
INSERT DummyTrans VALUES ('Fill Log') I WKq_Zjkz
DELETE DummyTrans wm~35cF(
SELECT @Counter = @Counter + 1 TG9 a1q
END 4\
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EXEC (@TruncLog) -l)vl<}
END [AkL6
SELECT 'Final Size of ' + db_name() + ' LOG is ' + !m8MyZ}%
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + 4H'\nsM
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' x9Um4!/t
FROM sysfiles l# u$w&
WHERE name = @LogicalFileName I^S
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DROP TABLE DummyTrans 0'q&7
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SET NOCOUNT OFF E{x<P0 ;
8、说明:更改某个表 mh&wvT<:{
exec sp_changeobjectowner 'tablename','dbo' 6BK-(>c(6
9、存储更改全部表 k?]`PUrV
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch h=h4`uA9
@OldOwner as NVARCHAR(128), =y+gS%o$
@NewOwner as NVARCHAR(128) sI\v}$(~
AS OZ>w.$ue
DECLARE @Name as NVARCHAR(128) B8A-|S!,U
DECLARE @Owner as NVARCHAR(128) e>z
DECLARE @OwnerName as NVARCHAR(128) B!{vSBq
DECLARE curObject CURSOR FOR Z./$}tVUG
select 'Name' = name, %;ST7
'Owner' = user_name(uid) E;m]RtvH
from sysobjects VRden>vKN
where user_name(uid)=@OldOwner DmzK* O{
order by name
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OPEN curObject 0?c2=Y
FETCH NEXT FROM curObject INTO @Name, @Owner cW%QKdTQY0
WHILE(@@FETCH_STATUS=0) ! Rr k
BEGIN j#4 Iu&YJ
if @Owner=@OldOwner Sd[%$)scC
begin tNpBRk(}
set @OwnerName = @OldOwner + '.' + rtrim(@Name) [ye!3h&]
exec sp_changeobjectowner @OwnerName, @NewOwner pY@$N&+W
end -u+@5K;^Y
-- select @name,@NewOwner,@OldOwner *UL++/f
FETCH NEXT FROM curObject INTO @Name, @Owner ~4gOv
END J:W|2U="
close curObject 4-j3&(
deallocate curObject _yx~t
GO 2S%[YR>>
10、SQL SERVER中直接循环写入数据 !@>_5p>q*
declare @i int RHO| g0
set @i=1 |T`ZK?B+u
while @i<30 3an9Rb V
begin YA+jLy6ZL
insert into test (userid) values(@i) YkWv*l
set @i=@i+1 arVu`pD*n
end ki|KtKAu_9
小记存储过程中经常用到的本周,本月,本年函数 bsClw
Dateadd(wk,datediff(wk,0,getdate()),-1) 287g 5
Dateadd(wk,datediff(wk,0,getdate()),6) *LuR
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