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。 Xb6X'rY
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一、基础 J5e
1、说明:创建数据库 '=C)Hj[D
CREATE DATABASE database-name c}v>Mx
2、说明:删除数据库 ZFpi'u.&
drop database dbname MKzIY:ug
3、说明:备份sql server O
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--- 创建 备份数据的 device M6l S2
USE master D]X&Va
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' ^h
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--- 开始 备份 7%DA0.g
BACKUP DATABASE pubs TO testBack =kFZ2/P2t(
4、说明:创建新表 }TE4)vXs
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 7vO3+lT/Y;
根据已有的表创建新表: S bI7<_
A:create table tab_new like tab_old (使用旧表创建新表) E>>@X^ =
B:create table tab_new as select col1,col2... from tab_old definition only LgFF+z
5、说明:删除新表 qM%l
drop table tabname {WJ9!pA!lk
6、说明:增加一个列 w6FtDl$
Alter table tabname add column col type P(AcDG6K
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。 |rW,:&;
7、说明:添加主键: Alter table tabname add primary key(col) n1n->l*HGP
说明:删除主键: Alter table tabname drop primary key(col) s\&qvL1D
8、说明:创建索引:create [unique] index idxname on tabname(col....) }\Kki
删除索引:drop index idxname ukNB#2"
注:索引是不可更改的,想更改必须删除重新建。 .rpKSf.
9、说明:创建视图:create view viewname as select statement is`O,Met
删除视图:drop view viewname N~Zcrt_D
10、说明:几个简单的基本的sql语句 R8ZI}C1
选择:select * from table1 where 范围 En-BT0o
插入:insert into table1(field1,field2) values(value1,value2) (Klvctoy
删除:delete from table1 where 范围 t$+[(}@+
更新:update table1 set field1=value1 where 范围 Z
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查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! Q|T9tc->
排序:select * from table1 order by field1,field2 [desc] tA;#yM;
总数:select count as totalcount from table1 cvSr><(
求和:select sum(field1) as sumvalue from table1 ~d5f]6#`
平均:select avg(field1) as avgvalue from table1 q8 jI
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最大:select max(field1) as maxvalue from table1 Igb@aGA
最小:select min(field1) as minvalue from table1 2x3%*r$
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11、说明:几个高级查询运算词 #>)OLKP
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A: UNION 运算符 ]CLt Km
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。 XNZW J
B: EXCEPT 运算符 s,~)5nL
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。 >2kjd
C: INTERSECT 运算符 Owt|vceT
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。 zNg8Oq&
注:使用运算词的几个查询结果行必须是一致的。 67,@*cK3?J
12、说明:使用外连接 `]*BDSvE
A、left outer join: #ArMX3^+w7
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。 d4(!9O.\
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 w+MCOAB
B:right outer join: !u0|{6U
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。 (zv)cw%
C:full outer join: (>.+tq}
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。 ~m0l_:SF
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二、提升 TOUP.,f/!
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) \7l%@
法一:select * into b from a where 1<>1 &uX|Ksq
法二:select top 0 * into b from a cwK+{*ZH/
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) ;`p!/9il
insert into b(a, b, c) select d,e,f from b; %+Az
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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) %BV2 q
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 )'pc 1I
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. ?A]@$
4、说明:子查询(表名1:a 表名2:b) c+_F}2)
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) '5:P,1tWU
5、说明:显示文章、提交人和最后回复时间 6e%|.}U
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b ]E8S`[Vn
6、说明:外连接查询(表名1:a 表名2:b) qjc8 $#zXS
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c qYi<GI*|@
7、说明:在线视图查询(表名1:a ) gr&Rkuyfv
select * from (SELECT a,b,c FROM a) T where t.a > 1; <;T$?J9
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 {\87]xJ
select * from table1 where time between time1 and time2 Hf^Tok^6@]
select a,b,c, from table1 where a not between 数值1 and 数值2 cag9f?w@V
9、说明:in 的使用方法 |N^z=g P[
select * from table1 where a [not] in ('值1','值2','值4','值6') c"<bq}L7S
10、说明:两张关联表,删除主表中已经在副表中没有的信息 N=?! ~n9Q-
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) "?[7oI}c&
11、说明:四表联查问题: $hCPmiI
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... >WKlR` J%
12、说明:日程安排提前五分钟提醒 (l~3~n
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 BUp,bJpO
13、说明:一条sql 语句搞定数据库分页 @['4 X1pqt
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 q/|WkV `m
14、说明:前10条记录 .*0`}H+_
select top 10 * form table1 where 范围 \K,piCVViN
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) ZJ|@^^GcL
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) tOu:j [
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 x>E**a?!L
(select a from tableA ) except (select a from tableB) except (select a from tableC) X*cf|g
17、说明:随机取出10条数据 @C}Hx;f6
select top 10 * from tablename order by newid() rwRb
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18、说明:随机选择记录 5[1#d\QR
select newid() pPezy:
19、说明:删除重复记录 l}Fa-9_'
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) m4@f&6x
20、说明:列出数据库里所有的表名 p| #gn<z}
select name from sysobjects where type='U' O8J:Tw}M*
21、说明:列出表里的所有的 +.p$Yi`
select name from syscolumns where id=object_id('TableName') 6BPZ2EQ
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。 |B0.*te6
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 e>oE{_e
显示结果: fK$N|r
type vender pcs _:tclBc8R
电脑 A 1 c=-2c&=&
电脑 A 1 q|8p4X}/]
光盘 B 2 /_,} o7@t~
光盘 A 2 ~6hG"t]:
手机 B 3 5xEk 7g.
手机 C 3 i N}BMd.U
23、说明:初始化表table1 <_|H]^o
TRUNCATE TABLE table1 bnWKfz5
24、说明:选择从10到15的记录 JKFV7{%Gl
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc
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三、技巧 `tCOe
1、1=1,1=2的使用,在SQL语句组合时用的较多 K7x,>
"where 1=1" 是表示选择全部 "where 1=2"全部不选, ,yC-QFQE
如: oc2aE:>X
if @strWhere !='' x%;Q
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begin Kk^tQwj/QE
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere jaoGm$o>"F
end iZ`1Dzxgk
else us.+nnd
begin ~YuRi#CTD:
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' |sw&sfH[FD
end AR}M*sSh
我们可以直接写成 9u 'hCi(
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere 3,K*r"=
2、收缩数据库 IXSCYqoK
--重建索引 GMw|@?:{
DBCC REINDEX lB\"*K;
DBCC INDEXDEFRAG S*H :/Ip
--收缩数据和日志 bW`@9 =E
DBCC SHRINKDB )-3!-1
DBCC SHRINKFILE 1m/=MET]
3、压缩数据库 u&=SZX&G k
dbcc shrinkdatabase(dbname) *5i~N}
4、转移数据库给新用户以已存在用户权限 $E^#DjhRQ3
exec sp_change_users_login 'update_one','newname','oldname' 4LU'E%vlC
go !d1}IU-h
5、检查备份集 D&WXa|EOK
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' -S=Zsr\
6、修复数据库 HA{-XPAWZ
ALTER DATABASE [dvbbs] SET SINGLE_USER 6,Q{/
GO ^}2 ie|
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK Qa,^;hZWS
GO lPS A
ALTER DATABASE [dvbbs] SET MULTI_USER 5JbPB!5;
GO 'DQp
7、日志清除 t[6 g9 e$
SET NOCOUNT ON S?{|qlpy
DECLARE @LogicalFileName sysname, Sa&~\!0t
@MaxMinutes INT, -(n[^48K
@NewSize INT 6TE RQ
USE tablename -- 要操作的数据库名 ?l_>rSly5
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名
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@MaxMinutes = 10, -- Limit on time allowed to wrap log. b'$j* N
@NewSize = 1 -- 你想设定的日志文件的大小(M) yaf&SR@7k{
-- Setup / initialize ^i{B8]2,
DECLARE @OriginalSize int %*.;3;m
SELECT @OriginalSize = size (8s]2\/Ar
FROM sysfiles j$*]'s&_hZ
WHERE name = @LogicalFileName -Uz
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SELECT 'Original Size of ' + db_name() + ' LOG is ' + 1K'0ajl1A
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + h^P>pI~
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' %PG::b
FROM sysfiles y(:hN)
WHERE name = @LogicalFileName `4cs.ab
CREATE TABLE DummyTrans r'hr'wZ
(DummyColumn char (8000) not null) #R|M(Z">q
DECLARE @Counter INT, `hM:U
@StartTime DATETIME, 'f`~"@
@TruncLog VARCHAR(255) O.=~/!(
SELECT @StartTime = GETDATE(), {6<7M
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' )o[ O%b
DBCC SHRINKFILE (@LogicalFileName, @NewSize) h<*l=`#
EXEC (@TruncLog) xZ@H{):
-- Wrap the log if necessary. z9$x9u
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired VEd#LSh
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) V/+r"le
AND (@OriginalSize * 8 /1024) > @NewSize a4,bP*H
BEGIN -- Outer loop. :~^ec|tp
SELECT @Counter = 0 qy@gW@IU
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) |xH"Xvp:
BEGIN -- update J`O4]XRY
INSERT DummyTrans VALUES ('Fill Log') 1!\!3xa V
DELETE DummyTrans xIF
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SELECT @Counter = @Counter + 1 RlX;c!K
END GI$t8{M
EXEC (@TruncLog) ',0~ \V
END ) BTJs)E
SELECT 'Final Size of ' + db_name() + ' LOG is ' + ]}9y>+>
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + $B4}('&4FQ
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' `QR2!W70o3
FROM sysfiles N_L&!%s
WHERE name = @LogicalFileName n?pCMS|
DROP TABLE DummyTrans .jr1<LE
SET NOCOUNT OFF Ta!.oC[
8、说明:更改某个表 Ts;W,pgP
exec sp_changeobjectowner 'tablename','dbo' *6Rl[eXS
9、存储更改全部表 'N5qX>Ob
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch 1X2oz
@OldOwner as NVARCHAR(128), m7kDxs(KO
@NewOwner as NVARCHAR(128) U:MkA(S%c
AS ~u8}s4
DECLARE @Name as NVARCHAR(128) aQN`C{nY
DECLARE @Owner as NVARCHAR(128) AnPm5i.
DECLARE @OwnerName as NVARCHAR(128) /[[zAq{OA
DECLARE curObject CURSOR FOR O6OP{sb
select 'Name' = name, 9Pd~
'Owner' = user_name(uid) %@Ks<"9
from sysobjects PZpwi?N
where user_name(uid)=@OldOwner ~>D;2 S(a
order by name OP2!lEs
OPEN curObject da!N0\.1T
FETCH NEXT FROM curObject INTO @Name, @Owner HtEjM|zj
WHILE(@@FETCH_STATUS=0) ER5Q` H
BEGIN S
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if @Owner=@OldOwner qB]z"Hfq,
begin dWD,iO_"@
set @OwnerName = @OldOwner + '.' + rtrim(@Name) {L$b$u$7:
exec sp_changeobjectowner @OwnerName, @NewOwner W\U zw,vI
end -ihF)^"a
-- select @name,@NewOwner,@OldOwner }#<Sq57n
FETCH NEXT FROM curObject INTO @Name, @Owner )dF(5,y)
END A>>@&c:(
close curObject P>pkLP}
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deallocate curObject R_vZh|
GO 8+gx?pb
10、SQL SERVER中直接循环写入数据 'xStA
declare @i int 7!oqn'#>A
set @i=1 .1I];Cy0D
while @i<30 r'&9'rir2
begin }jiqUBn%
insert into test (userid) values(@i) ADv
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set @i=@i+1 lbg6n:@
end 7@EYF
小记存储过程中经常用到的本周,本月,本年函数 cw"x0 RS
Dateadd(wk,datediff(wk,0,getdate()),-1) _gC<%6#V`r
Dateadd(wk,datediff(wk,0,getdate()),6) {, APZ`q|
Dateadd(mm,datediff(mm,0,getdate()),0) c#"\&~. P
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) _5
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Dateadd(yy,datediff(yy,0,getdate()),0) f,M$>!$V
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) AV d
上面的SQL代码只是一个时间段 @dCu]0oNI
Dateadd(wk,datediff(wk,0,getdate()),-1) #4na>G|
Dateadd(wk,datediff(wk,0,getdate()),6) #yr19i ?
就是表示本周时间段. FbFUZ^Zj
下面的SQL的条件部分,就是查询时间段在本周范围内的: d*A >P
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) 1uV_C[:
而在存储过程中 ,C&h~uRi#f
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) Bf'jXM{-
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) }%k"qW<Y