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。 z1s"C[W2T
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一、基础 |R/50axI
1、说明:创建数据库 AB\4+ CLV
CREATE DATABASE database-name n5>N9lc
2、说明:删除数据库 TJ:Lz]l >
drop database dbname {hR2NUm
3、说明:备份sql server :q1r2&ne
--- 创建 备份数据的 device $7d"9s\$"
USE master $u"$mg7x
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' ??V["o T
--- 开始 备份 R,1 ,4XT
BACKUP DATABASE pubs TO testBack ^0-=(JrC
4、说明:创建新表 pk1M.+
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) hiHp@"l<
根据已有的表创建新表: ?='9YM
A:create table tab_new like tab_old (使用旧表创建新表) \9QOrjiw
B:create table tab_new as select col1,col2... from tab_old definition only V1A3l{>L
5、说明:删除新表 .p>8oOp
drop table tabname nTKfwIeg5
6、说明:增加一个列 =>*N W9c
Alter table tabname add column col type rSn7(3e4^
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。 q8>Q,F`BA
7、说明:添加主键: Alter table tabname add primary key(col) |Wk
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说明:删除主键: Alter table tabname drop primary key(col) 3k^jR1
8、说明:创建索引:create [unique] index idxname on tabname(col....) m5{SPa,y
删除索引:drop index idxname !F)oX7"
注:索引是不可更改的,想更改必须删除重新建。 bp,CvQ'}a
9、说明:创建视图:create view viewname as select statement EdpR| z
删除视图:drop view viewname qDAjW)w
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10、说明:几个简单的基本的sql语句 T<)z2Bi
选择:select * from table1 where 范围 M7 !"
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插入:insert into table1(field1,field2) values(value1,value2) E76:}(
删除:delete from table1 where 范围 BUyA]
更新:update table1 set field1=value1 where 范围 --kK<9J7
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! P\e%8&_U/
排序:select * from table1 order by field1,field2 [desc] >`'9V|1
总数:select count as totalcount from table1 a~>h'}C>
求和:select sum(field1) as sumvalue from table1 :6V8
平均:select avg(field1) as avgvalue from table1 Q>$L;1E*,
最大:select max(field1) as maxvalue from table1 kM`#U
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最小:select min(field1) as minvalue from table1 9l]IE,u
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11、说明:几个高级查询运算词 e_V(G
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A: UNION 运算符 H
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UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 7l3q~ dQ
B: EXCEPT 运算符 q=6Y2Q
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 A4' aB0^
C: INTERSECT 运算符 @jKB!z9{
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 K>y+3HN[6
注:使用运算词的几个查询结果行必须是一致的。 <H 6Uo#ao
12、说明:使用外连接 %R"Fx$tQ
A、left outer join: {wI0 =U
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。 -S@:
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 X)m2{@v D
B:right outer join: {'!~j!1'j
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。 h#
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C:full outer join: 2|BE{91
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。 -;}Wm[
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二、提升 rej[G!
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) t
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法一:select * into b from a where 1<>1 *Y Ox`z!R
法二:select top 0 * into b from a whCv9)x
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) v(`$%V.
insert into b(a, b, c) select d,e,f from b; M .,|cx
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) 2uIAnbW]M
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 vaL-Mi(_
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. z@~rm9d
4、说明:子查询(表名1:a 表名2:b)
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select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) 5S LF1u;
5、说明:显示文章、提交人和最后回复时间 zlE kP @)
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b >pKI'
6、说明:外连接查询(表名1:a 表名2:b) Sf9+TW
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c #x21e }Li
7、说明:在线视图查询(表名1:a ) bxs@_fH
select * from (SELECT a,b,c FROM a) T where t.a > 1; z61
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8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 R9(^CWs
select * from table1 where time between time1 and time2 -|mABHjx*
select a,b,c, from table1 where a not between 数值1 and 数值2 GF&"nW9A
9、说明:in 的使用方法 5 *_#"
select * from table1 where a [not] in ('值1','值2','值4','值6') X}$S|1CjO
10、说明:两张关联表,删除主表中已经在副表中没有的信息 Dg`W{oj
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) Cb.Aw!
11、说明:四表联查问题: Lst5
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 ..... (C&f~U
12、说明:日程安排提前五分钟提醒 lV8Mr6m
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 N5^:2ag
13、说明:一条sql 语句搞定数据库分页 =E}/Z
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 _EP}el
14、说明:前10条记录 I$$!YMm.N
select top 10 * form table1 where 范围 %:lQ ~yn
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.) i&Ea@b
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) \T0`GpE
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 BeQJ/`
(select a from tableA ) except (select a from tableB) except (select a from tableC) eW/Hn
17、说明:随机取出10条数据 _N6GV$Q
select top 10 * from tablename order by newid() ~&kV
18、说明:随机选择记录 TUG3#PSnm*
select newid() =B 9U
19、说明:删除重复记录 xQQ6D
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) 0!Yi.'+
20、说明:列出数据库里所有的表名
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select name from sysobjects where type='U' ;I>`!|mT
21、说明:列出表里的所有的 +xMDm_TGLA
select name from syscolumns where id=object_id('TableName') RaAq>B
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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。 3I]5DW %-
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 ]#`bYh^y
显示结果: [{YV<kN
type vender pcs %llG/]q#
电脑 A 1 ~c4Y*]J
电脑 A 1 Ae1},2py
光盘 B 2 [*fnTy
光盘 A 2 t1kD5^
手机 B 3 nP.d5%E
手机 C 3 3hkA`YSYt
23、说明:初始化表table1 piU4%EO
TRUNCATE TABLE table1 ,M9'S;&^
24、说明:选择从10到15的记录 ]Sh&8 #
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc ][3 "xP
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三、技巧 sB $!X@
1、1=1,1=2的使用,在SQL语句组合时用的较多 .$Y[>9
"where 1=1" 是表示选择全部 "where 1=2"全部不选, B6BOy~B0
如: QFMS]
if @strWhere !='' ZEW`?6
begin uaiG(O
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere PqfH}d0l
end pcE.
else gbvBgOp
begin TWy1)30x
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' il:""x7^y
end epQ7@9,Q
我们可以直接写成 xaPTTa
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere 1*XqwBV
2、收缩数据库 D`u{U]
--重建索引 Ou/{PK}
DBCC REINDEX mWZVO,t$
DBCC INDEXDEFRAG A/9 w r
--收缩数据和日志 H=0Y4 T@)T
DBCC SHRINKDB [.2>=3T
DBCC SHRINKFILE fSj^/>
3、压缩数据库 f.!cR3XgV
dbcc shrinkdatabase(dbname) ~`y6YIJ3
4、转移数据库给新用户以已存在用户权限 B|!Re4`0
exec sp_change_users_login 'update_one','newname','oldname' 0'gJSrgNI
go )pg?Z M9
5、检查备份集 ;(z0r_p<q
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' uJi|@{V
6、修复数据库 fNQecDuS
ALTER DATABASE [dvbbs] SET SINGLE_USER {L#Pdj{
GO h>4\I;Ij
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK C3|M\[*fp
GO !O*\|7A(
ALTER DATABASE [dvbbs] SET MULTI_USER <|v]9`'
GO VP[ J#TPU
7、日志清除 zzM 'uo
SET NOCOUNT ON C@xh$(y
DECLARE @LogicalFileName sysname, 86[TBX5'
@MaxMinutes INT, TtHqdKL
@NewSize INT o_?YYw-:
USE tablename -- 要操作的数据库名 -q[?,h
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 J
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@MaxMinutes = 10, -- Limit on time allowed to wrap log. bEM-^SR
@NewSize = 1 -- 你想设定的日志文件的大小(M) ^*Sb)tu\ W
-- Setup / initialize j#29L"
DECLARE @OriginalSize int ^X^4R1V)
SELECT @OriginalSize = size X[R/j*K
FROM sysfiles U`xjau+
WHERE name = @LogicalFileName >XBLm`a
SELECT 'Original Size of ' + db_name() + ' LOG is ' + 1D 6iJ
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + u\50,N9Wp{
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' YI|7a#*F
FROM sysfiles E#J+.&2
WHERE name = @LogicalFileName -|g~--@Q
CREATE TABLE DummyTrans 0C7x1:
(DummyColumn char (8000) not null) G"wy?
DECLARE @Counter INT, 0Y{A
@StartTime DATETIME, yKi* 8N"e<
@TruncLog VARCHAR(255) ^dQ#\uy
SELECT @StartTime = GETDATE(), _Y=>^K]9K
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' ?,]25q
DBCC SHRINKFILE (@LogicalFileName, @NewSize) oTZNW
EXEC (@TruncLog) _E3*;
-- Wrap the log if necessary. *U8Pjb1
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired k\A8Z[
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) ]"^U
AND (@OriginalSize * 8 /1024) > @NewSize -Zkl\A$>
BEGIN -- Outer loop. G >bQlZG
SELECT @Counter = 0 c{zQX0
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) >a[)F
BEGIN -- update q'[5h>Pa
INSERT DummyTrans VALUES ('Fill Log') 4&}LYSZl
DELETE DummyTrans 2}K7(y!?u
SELECT @Counter = @Counter + 1 0X.pI1jCO
END UE5T%zd /
EXEC (@TruncLog) S-*4HV_l
END tv5G']vO\
SELECT 'Final Size of ' + db_name() + ' LOG is ' + 6Z0@4_Y@B6
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + ml\A)8O]j/
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' $0
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FROM sysfiles 3V2"1Ic
WHERE name = @LogicalFileName (]1n!
DROP TABLE DummyTrans
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SET NOCOUNT OFF \IIR2Xf,K
8、说明:更改某个表 I!~5.
exec sp_changeobjectowner 'tablename','dbo' k68\ _ NUL
9、存储更改全部表 x8w455
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch 6|L<?
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@OldOwner as NVARCHAR(128), >2TDYB|;
@NewOwner as NVARCHAR(128) ^ 14U]<
AS NZ7g}+GTG
DECLARE @Name as NVARCHAR(128) m\RU|Z
DECLARE @Owner as NVARCHAR(128) O)n"a\LD
DECLARE @OwnerName as NVARCHAR(128) eNR>W>;'
DECLARE curObject CURSOR FOR ZG3u
select 'Name' = name, xx_]e4
'Owner' = user_name(uid) g ?qm >X
from sysobjects
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where user_name(uid)=@OldOwner x[zt(kC0+
order by name !K'j[cA^
OPEN curObject P;C3{>G9
FETCH NEXT FROM curObject INTO @Name, @Owner N[:;f^bH49
WHILE(@@FETCH_STATUS=0) [2:Q.Zj
BEGIN )l~:Puvh
if @Owner=@OldOwner "8>T
begin N*y09?/h
set @OwnerName = @OldOwner + '.' + rtrim(@Name) E0[ec6^qwY
exec sp_changeobjectowner @OwnerName, @NewOwner !`JaYUL[e
end /I(IT=kp
-- select @name,@NewOwner,@OldOwner Y j;KKgk
FETCH NEXT FROM curObject INTO @Name, @Owner ~dg7c{o5
END D6fry\
close curObject >{C=\F#*L
deallocate curObject JHC 6l
GO Yi1lvB?m
10、SQL SERVER中直接循环写入数据 ]3nka$wA*
declare @i int .5Sw
set @i=1 tNj-~r
while @i<30 mII7p LbQ
begin ..'k+0u^
insert into test (userid) values(@i) cks53/Z
set @i=@i+1 ~PAF2
end $dIu${lu
小记存储过程中经常用到的本周,本月,本年函数 >MwjUq
Dateadd(wk,datediff(wk,0,getdate()),-1) 78T9"CS
Dateadd(wk,datediff(wk,0,getdate()),6) lV<2+Is
Dateadd(mm,datediff(mm,0,getdate()),0) LQ(z~M0B
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) ~gg(i"V
Dateadd(yy,datediff(yy,0,getdate()),0) 6aRPm%
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) <pyLWmO
上面的SQL代码只是一个时间段
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Dateadd(wk,datediff(wk,0,getdate()),-1) v,Eqn8/O
Dateadd(wk,datediff(wk,0,getdate()),6) dY[ XNP
就是表示本周时间段. 2O;Lw@W
下面的SQL的条件部分,就是查询时间段在本周范围内的: 8`~M$5!
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) uyZ
而在存储过程中 P@lDhzd
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) u_ou,RF
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) S{wR Z|8U