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。 aAJ'0xnj
p}I,!~}
d)d\h`=Z
一、基础 {kVhht]X
1、说明:创建数据库 S &N[@G
CREATE DATABASE database-name VjsQy>5m
2、说明:删除数据库 U(*k:Fw
drop database dbname kB:6e7D|[
3、说明:备份sql server AM?62
--- 创建 备份数据的 device C^2J<
USE master Cp {
j+Ia
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' &b~if}vcb
--- 开始 备份 ` 9iB`<
BACKUP DATABASE pubs TO testBack lM/)<I\8
4、说明:创建新表 Ni bOtIZ
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) ]A.:8;
根据已有的表创建新表: E3%:7MB
A:create table tab_new like tab_old (使用旧表创建新表) q3Tp/M.
B:create table tab_new as select col1,col2... from tab_old definition only k?[|8H~2C
5、说明:删除新表 57PoJ+
drop table tabname [R-&5 G!x
6、说明:增加一个列 GO3F[l
Alter table tabname add column col type Y367Jr@^N
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。 =\u QGH
7、说明:添加主键: Alter table tabname add primary key(col) wX7|a/|@
说明:删除主键: Alter table tabname drop primary key(col) c:>&iB-Yu
8、说明:创建索引:create [unique] index idxname on tabname(col....) ZoFQJJK56B
删除索引:drop index idxname xweV8k/
注:索引是不可更改的,想更改必须删除重新建。 YI0ubB
9、说明:创建视图:create view viewname as select statement 3"9'MDKH
删除视图:drop view viewname GP|G[
10、说明:几个简单的基本的sql语句 p:g`K#[F
选择:select * from table1 where 范围 $;@LPE
插入:insert into table1(field1,field2) values(value1,value2) +T\c<lJ9
删除:delete from table1 where 范围 B{`4"uEb$G
更新:update table1 set field1=value1 where 范围 ea7l:(C
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! <S/`-/=2
排序:select * from table1 order by field1,field2 [desc]
LY>-kz]
总数:select count as totalcount from table1 8~q%H1[I\N
求和:select sum(field1) as sumvalue from table1 ;ndsq[k>
平均:select avg(field1) as avgvalue from table1 <Vu/6"DP
最大:select max(field1) as maxvalue from table1 {Ftz4y)6
最小:select min(field1) as minvalue from table1 +=Xgi$
02|f@bP.
Gn+3OI"
$mS]K!\
11、说明:几个高级查询运算词 39j "z8n
I)9un|+,y
!+Ia#(
A: UNION 运算符 \:`'!X1*U
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。 r&qFv)0!`
B: EXCEPT 运算符 OanH G
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。 r@j$$Pk`
C: INTERSECT 运算符 d`M]>EDXp
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。 zzq7?]D
注:使用运算词的几个查询结果行必须是一致的。 \(m_3 H
12、说明:使用外连接 -&3WN!egq
A、left outer join: H?ZlJ|/c
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。 ` #!~+
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 Ujw J}j
B:right outer join: }1N$4@
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 vO2I"Y*\
C:full outer join: C9?R*2L>
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 !%pY)69gv
+s(JutC
4s{_(gy
二、提升 y]z^e\qc)
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) DBUhqRfl
法一:select * into b from a where 1<>1 E Z^eEDZ
法二:select top 0 * into b from a 3F/05}d`
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) ]yzqBbV
insert into b(a, b, c) select d,e,f from b; }M9R5!=q
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) )@%wj;>a
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 0H|U9
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. )T4%}$(
4、说明:子查询(表名1:a 表名2:b) H[K(Tt4<&
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) hX?rIx
5、说明:显示文章、提交人和最后回复时间 (
Lp~:p
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b -85]x)JE
6、说明:外连接查询(表名1:a 表名2:b) ~hJ/&,vH!
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c ;THb6Jz/+
7、说明:在线视图查询(表名1:a ) M!KHBr
select * from (SELECT a,b,c FROM a) T where t.a > 1; (6Ssk4
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 8(GH.)I+0
select * from table1 where time between time1 and time2 ,(%?j]_P2
select a,b,c, from table1 where a not between 数值1 and 数值2 <4caG2~q
9、说明:in 的使用方法 m~upTQz
select * from table1 where a [not] in ('值1','值2','值4','值6') 8|\0\Wd;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 |sa{!tKJ
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) NS^(5g
11、说明:四表联查问题: iti~RV,
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 ..... QH_0U`3
12、说明:日程安排提前五分钟提醒 o_!=-AWV
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5
l?_h(Cq<
13、说明:一条sql 语句搞定数据库分页 '/Y
D$*,
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 j _r?4k
14、说明:前10条记录 8XwZJ\5
select top 10 * form table1 where 范围 "X\|!Mxh
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.) f^
q0#+k )
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) .I6:iB
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 }7`HJ>+m)H
(select a from tableA ) except (select a from tableB) except (select a from tableC) H<^*V8J 'w
17、说明:随机取出10条数据 $Vu%4kq
select top 10 * from tablename order by newid() ]e*Zx;6oi
18、说明:随机选择记录 81O\BO.T
select newid() RC[b+J,q
19、说明:删除重复记录 OHz>B!`
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) SAuZWA4g[
20、说明:列出数据库里所有的表名 76Drhh(
select name from sysobjects where type='U' tb%u<jY
21、说明:列出表里的所有的 NT qtr="
select name from syscolumns where id=object_id('TableName') aD2+9?m
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。 Jd].e=]pN
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 kG =nDy
显示结果: rZ.,\ X_
type vender pcs kh11Y1Q0d
电脑 A 1 w|~d3]BqT
电脑 A 1 yMdAe>@
光盘 B 2 6usy0g
D
光盘 A 2 lq4vX^S
手机 B 3 Lk%u(duU^
手机 C 3 U#o5(mK
23、说明:初始化表table1 ?dWfupO{
TRUNCATE TABLE table1 $On
24、说明:选择从10到15的记录 /}_OCuJJ,
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc -jBk
fS( )F*J
KNR_upO8
.zm'E<
三、技巧 RVlAWw(
1、1=1,1=2的使用,在SQL语句组合时用的较多 c"vF i~Db
"where 1=1" 是表示选择全部 "where 1=2"全部不选, 3f 1@<7*
如: q&eUw<(F
if @strWhere !='' M<f=xY2$v
begin "8pfLI
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere 2TR l@
end &4aY5y`8+f
else qr5ME/)z
begin hq5=>p
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' Ihe/P {t]J
end /+FZDRf!r
我们可以直接写成 f z)i9D@
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere W*'gqwM&
2、收缩数据库 Jk$XL<t
--重建索引 <Pg]V:=g'
DBCC REINDEX 9.bMA<X
DBCC INDEXDEFRAG x]({Po4
--收缩数据和日志 ;%Z%]nIS
DBCC SHRINKDB Tum9Xa
DBCC SHRINKFILE %h"+J
3、压缩数据库 6bL"Z OEu
dbcc shrinkdatabase(dbname) 9*?H/iN@p?
4、转移数据库给新用户以已存在用户权限 }v0IzGKs
exec sp_change_users_login 'update_one','newname','oldname' 0baq696<F
go T>"GH M
5、检查备份集 Ek!$Ary
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' ?V6+o`bm
6、修复数据库 QlbhQkn
ALTER DATABASE [dvbbs] SET SINGLE_USER DYvi1X6
GO 8"C;I=]8
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK Jm%hb,
GO ^1&xt(G
ALTER DATABASE [dvbbs] SET MULTI_USER .x$!Rc}
GO (qE*z
7、日志清除 /o<tmK_m
SET NOCOUNT ON w|6;Pf~1y)
DECLARE @LogicalFileName sysname, jGB2`^&d
@MaxMinutes INT, @!92Ok
@NewSize INT dHU#Y,v
USE tablename -- 要操作的数据库名 x;RjLI 4h
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 G$ l>By
@MaxMinutes = 10, -- Limit on time allowed to wrap log. 6B4s6
@NewSize = 1 -- 你想设定的日志文件的大小(M) vXUrS+~x
-- Setup / initialize XxW~4<r
DECLARE @OriginalSize int (t.pM P4
SELECT @OriginalSize = size yFt'<{z[nL
FROM sysfiles cZ(7/Pl
WHERE name = @LogicalFileName
b;!oPT
SELECT 'Original Size of ' + db_name() + ' LOG is ' + st;.Po[h
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + Fm\
h883\
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' Dh*>361y-
FROM sysfiles GHQa{@m2V
WHERE name = @LogicalFileName nwd
02tu
CREATE TABLE DummyTrans :K!@zT=o
(DummyColumn char (8000) not null) @@U'I^iG
DECLARE @Counter INT, >\Qyg>Md]
@StartTime DATETIME, WMB~?
EDhv
@TruncLog VARCHAR(255) JwzA'[tM
SELECT @StartTime = GETDATE(), w%,Iy,G@
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' tS2 P|fl
DBCC SHRINKFILE (@LogicalFileName, @NewSize) ]xf
lfZ
EXEC (@TruncLog) 7y",%WYSD
-- Wrap the log if necessary. Qtmsk:qm
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired ~%Y*2i
f
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) jW6~^>S
AND (@OriginalSize * 8 /1024) > @NewSize q#v&&]N=
BEGIN -- Outer loop. ~o:lh],~
SELECT @Counter = 0 ojO<sT:by
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) P |c6V
BEGIN -- update A[lkGQtS4
INSERT DummyTrans VALUES ('Fill Log') .tB[8Y =J
DELETE DummyTrans
D7%`hU
SELECT @Counter = @Counter + 1 S3-3pJ]~Zk
END aHKv*-z-
EXEC (@TruncLog) KZn\ iwj
END L+@RK6dq
SELECT 'Final Size of ' + db_name() + ' LOG is ' + M9MfO*
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + u</21fz'
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' ~ifo7,
FROM sysfiles UzVnC:
WHERE name = @LogicalFileName P,Fs7
DROP TABLE DummyTrans Aa*UV6(v
SET NOCOUNT OFF 3@e#E4+ff
8、说明:更改某个表 !+T9NqDv[
exec sp_changeobjectowner 'tablename','dbo' 7Rr(YoWa
9、存储更改全部表 rj"oz"
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch _20nOg`o
@OldOwner as NVARCHAR(128), #vJDb |z
@NewOwner as NVARCHAR(128) &Y"u*)bm
AS "}PaMR]
DECLARE @Name as NVARCHAR(128) D_,}lsrb
DECLARE @Owner as NVARCHAR(128) -#v1b>ScY
DECLARE @OwnerName as NVARCHAR(128)
=@b/Gl
DECLARE curObject CURSOR FOR >^%]F[Wo
select 'Name' = name, %WrUu|xj>_
'Owner' = user_name(uid) <J=9,tv<
from sysobjects |$`LsA.
where user_name(uid)=@OldOwner m(nGtrQJm
order by name ~={8b
OPEN curObject VsOn j~@
FETCH NEXT FROM curObject INTO @Name, @Owner =iy%;>I`
WHILE(@@FETCH_STATUS=0) TD+V.}
BEGIN X:\ r )
if @Owner=@OldOwner fZ6lnZ
begin tk4~ 8
set @OwnerName = @OldOwner + '.' + rtrim(@Name) yG?,8!/]
exec sp_changeobjectowner @OwnerName, @NewOwner bit&H
end //VgPl
-- select @name,@NewOwner,@OldOwner U7U-H\t7
FETCH NEXT FROM curObject INTO @Name, @Owner lmb5Z-xB
END qp>O#tj[
close curObject |yiM7U,i
deallocate curObject t&(}`W
GO C|c'V-f
10、SQL SERVER中直接循环写入数据 KFHn)+*"
declare @i int UJ1Ui'a(!!
set @i=1 D0,U2d
while @i<30 hVRpk0IJDK
begin #KZ6S9>@
insert into test (userid) values(@i) Ji SJi?
set @i=@i+1 hKb-l`KO
end 9J_lxy}
小记存储过程中经常用到的本周,本月,本年函数 X
b-q:{r1h
Dateadd(wk,datediff(wk,0,getdate()),-1) A P><l@
Dateadd(wk,datediff(wk,0,getdate()),6) g"|QI=&_J
Dateadd(mm,datediff(mm,0,getdate()),0) BY"<90kBL
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) >6 [{\uPK
Dateadd(yy,datediff(yy,0,getdate()),0) bLoAtI
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) agX-V{l.
上面的SQL代码只是一个时间段 6/B"H#rN
Dateadd(wk,datediff(wk,0,getdate()),-1) kpi)uGvGUA
Dateadd(wk,datediff(wk,0,getdate()),6) 92+LY]jS
就是表示本周时间段. 49&p~g
下面的SQL的条件部分,就是查询时间段在本周范围内的: V*SKWP
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) +=hiLfnE
而在存储过程中 M >Yx_)<U
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) 4AB7 uw
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) )~;= 0O |X