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。 G=&nwSL
8b< 'jft
WNF#eM?[a
一、基础 %VS+?4ww
1、说明:创建数据库
M 9KoQS
CREATE DATABASE database-name 4E@_Fn_#
2、说明:删除数据库 VVk8z6W
drop database dbname u_6x{",5I
3、说明:备份sql server Jm,tN/o*
--- 创建 备份数据的 device &e99P{\D
USE master \`-a'u=S
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' _z53r+A
--- 开始 备份 s/Q8(sF5
BACKUP DATABASE pubs TO testBack rVB\\
4、说明:创建新表 )F4BVPI
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) ,YF1*69
根据已有的表创建新表: KdC'#$
A:create table tab_new like tab_old (使用旧表创建新表) mJ+mTA5bW
B:create table tab_new as select col1,col2... from tab_old definition only 3+H[S#e:Z
5、说明:删除新表 @j=rSS
drop table tabname n"f:6|<
6、说明:增加一个列 j>#ywh*A
Alter table tabname add column col type 6!v$"u|[!'
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 vAfYONU
7、说明:添加主键: Alter table tabname add primary key(col) eDsc_5I
说明:删除主键: Alter table tabname drop primary key(col) 0+Q;a
8、说明:创建索引:create [unique] index idxname on tabname(col....) =21m|8c
删除索引:drop index idxname u|75r%p>
注:索引是不可更改的,想更改必须删除重新建。 t"X^|!hKIF
9、说明:创建视图:create view viewname as select statement 0}WDB_L
删除视图:drop view viewname :Q"p!,X=-
10、说明:几个简单的基本的sql语句 b ; U
选择:select * from table1 where 范围 YFeL#)5y
插入:insert into table1(field1,field2) values(value1,value2) ))E| SAr
删除:delete from table1 where 范围 63c\1]YB.
更新:update table1 set field1=value1 where 范围 64t:
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! !&R|P|7qN}
排序:select * from table1 order by field1,field2 [desc] a=M/0N{!
总数:select count as totalcount from table1 8j}o\!H
求和:select sum(field1) as sumvalue from table1 4c@_u8
平均:select avg(field1) as avgvalue from table1 1:Wl/9mL
最大:select max(field1) as maxvalue from table1 K1zH\wH
最小:select min(field1) as minvalue from table1 +$#ytvDy
"-g5$v$de
\ `|
bkiMF$K,K
11、说明:几个高级查询运算词 nT=XWM
ebhV;Q.
83_vo0@<6
A: UNION 运算符 CB`GiH/j
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。 ex8}./mjJ
B: EXCEPT 运算符 #&ayWef
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。 /hAy1V6
C: INTERSECT 运算符 cq}i)y
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。 afd.v$63
注:使用运算词的几个查询结果行必须是一致的。 Qb' Q4@.
12、说明:使用外连接 p']{WLDj2
A、left outer join: H6<3'P
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 Z5,"KhB]
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c *|6*jU
B:right outer join: K9) |b`E=
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 IgPU^?sp
C:full outer join: >Zh^,T={G
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 p$a+?5'Q
,D\}DJ`)C
(Ji=fh+
二、提升 &90pKs
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) *kt%.wPJ
法一:select * into b from a where 1<>1 UoHNKB73
法二:select top 0 * into b from a O}X@QG2_
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) g:Fo7*i
insert into b(a, b, c) select d,e,f from b; U3t)yr h
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) AA[?a
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 ;$FMOMR
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. 3W}qNY;J
4、说明:子查询(表名1:a 表名2:b) [uFv_G{H
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) L[MAc](me-
5、说明:显示文章、提交人和最后回复时间 jm,:jkr
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b v-}B
T+
6、说明:外连接查询(表名1:a 表名2:b) 6o~g3{Ow
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c g|5cO3m0'
7、说明:在线视图查询(表名1:a ) 2tZ\/6G<
select * from (SELECT a,b,c FROM a) T where t.a > 1; =Q4Wr0y><]
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 `Wp y6o
select * from table1 where time between time1 and time2 5E}!TL$
select a,b,c, from table1 where a not between 数值1 and 数值2
!qTP
9、说明:in 的使用方法 J/\^3rCB
select * from table1 where a [not] in ('值1','值2','值4','值6') 9XX:_9|I
10、说明:两张关联表,删除主表中已经在副表中没有的信息 pXK-,7-
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) M7//*Q'?
11、说明:四表联查问题: U[NQ"
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 ..... q1Ehl
S
12、说明:日程安排提前五分钟提醒 % E8s>D
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 @Op7OFY%
13、说明:一条sql 语句搞定数据库分页 O[z-K K<
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 S(G&{KG
14、说明:前10条记录 J1Oe`my
select top 10 * form table1 where 范围 tW%!|T5/
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.) Os1=V
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) a 9Kws[
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 T.q7~ba*
(select a from tableA ) except (select a from tableB) except (select a from tableC) EgTj
17、说明:随机取出10条数据 9HZR%s[J
select top 10 * from tablename order by newid() Sb?HRoe_
18、说明:随机选择记录 ,AyQCUz{*?
select newid() Mi7LyIu
19、说明:删除重复记录 UGQHwz
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) |yi#6!}^
20、说明:列出数据库里所有的表名 D}nIF7r2N
select name from sysobjects where type='U' <+AvbqDe
21、说明:列出表里的所有的 i:x<Vi
select name from syscolumns where id=object_id('TableName') L^??*XEUJ
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。 -"d&Ow7o
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 t ]P^6jw'
显示结果: 4Vv$bbu+
type vender pcs APq Yf<W
电脑 A 1 }W
nvz;]B
电脑 A 1 &cT@MV5
光盘 B 2 I?KGb:]|
光盘 A 2 "\rR0V!wA
手机 B 3 0"koZd,c
手机 C 3 Y#rd'
8
23、说明:初始化表table1 imZ"4HnPP
TRUNCATE TABLE table1 /C/I_S}H
24、说明:选择从10到15的记录 gS.,V!#t
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc U2*kuP+n
zj7?2
ilkN3J
;oVFcZSA
三、技巧 h&<>nK
1、1=1,1=2的使用,在SQL语句组合时用的较多 $mut v=IO
"where 1=1" 是表示选择全部 "where 1=2"全部不选, U_@Dn[/:
如: 7o$S6Y;c4
if @strWhere !='' rWN%Tai-
begin 9lc{{)m2)
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere Gr!@ih^
end )m>Y[)8!
else '%KaAi$
begin 9&'HhJm
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' {hBnEj^@
end sQ8kLS_q8
我们可以直接写成 mC./,a[
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere b^WF
R
2、收缩数据库 kB]*2o9-3
--重建索引 Q =4~uz|
DBCC REINDEX -5MQ/ujQ
DBCC INDEXDEFRAG |^ J5YwCf
--收缩数据和日志 BH2JH>'X
DBCC SHRINKDB bs?&;R.5
DBCC SHRINKFILE 2;`WI:nt
3、压缩数据库 DQ%(X&k
dbcc shrinkdatabase(dbname) 1NQU96
4、转移数据库给新用户以已存在用户权限 eRB
K= X
exec sp_change_users_login 'update_one','newname','oldname' xs$.EY:k
go X?n($z/{
5、检查备份集 MbyV_A`r_
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' zC>zkFT>H
6、修复数据库 m" c6^)U
ALTER DATABASE [dvbbs] SET SINGLE_USER HKG8X="
GO zQx6r
.
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK .[S\&uRv
GO -E-e!
ALTER DATABASE [dvbbs] SET MULTI_USER 7 MG<!U
GO F tay8m@f
7、日志清除 0hCUr]cZ,
SET NOCOUNT ON /H :Bu
DECLARE @LogicalFileName sysname, H<ZXe!q(nx
@MaxMinutes INT, |!uC [=
@NewSize INT :\"g}AX
USE tablename -- 要操作的数据库名 5 IFc"
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 y{J7^o(_~
@MaxMinutes = 10, -- Limit on time allowed to wrap log. $c7Utms
@NewSize = 1 -- 你想设定的日志文件的大小(M) %Hy.
-- Setup / initialize * a@78&N
DECLARE @OriginalSize int $fQ'q3
SELECT @OriginalSize = size =7Sw29u<
FROM sysfiles k;pU8y6Y
WHERE name = @LogicalFileName {/K!cPp9
SELECT 'Original Size of ' + db_name() + ' LOG is ' + Dj x[3['
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + #-K,,"
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' s+&iH
FROM sysfiles e/F+Tf
WHERE name = @LogicalFileName zd?uMq;w
CREATE TABLE DummyTrans nv%0EAa#}
(DummyColumn char (8000) not null) LqoH]AcN
DECLARE @Counter INT, nVGWJ3
@StartTime DATETIME, # &Z1d(!
@TruncLog VARCHAR(255) c{wob%!>
SELECT @StartTime = GETDATE(), %DuSco"
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' qz.WF8Sy2
DBCC SHRINKFILE (@LogicalFileName, @NewSize) /[>zFYaQ
EXEC (@TruncLog) E
rnGX#@v
-- Wrap the log if necessary. ts;C:.X
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired b0yNc:
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) 1'SpJL1u~
AND (@OriginalSize * 8 /1024) > @NewSize )C%S`d<%,
BEGIN -- Outer loop. tq2TiXo%
SELECT @Counter = 0 K#a_7/!v/
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) !-s 6B
BEGIN -- update uEDvdd#V.
INSERT DummyTrans VALUES ('Fill Log') >(eR0.x
DELETE DummyTrans [_zoJ
SELECT @Counter = @Counter + 1 o`7B@]
END
W>m#Mz
EXEC (@TruncLog) HQ`A.E2
END `lN
Z|U
SELECT 'Final Size of ' + db_name() + ' LOG is ' + f^ 6da6Z
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + );L +)UV
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' Z~HLa
FROM sysfiles 4/E>k <MA
WHERE name = @LogicalFileName -k}&{v
DROP TABLE DummyTrans -SKcS#IF
SET NOCOUNT OFF 4L)Ox;6>
8、说明:更改某个表 vff`Xh>k(
exec sp_changeobjectowner 'tablename','dbo' m,#Us
9、存储更改全部表 W Z^u%Z
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch +3k#M[Bn}
@OldOwner as NVARCHAR(128), wPH1g*U
@NewOwner as NVARCHAR(128) "Sd2VSLg
AS 4Q^i"jT
DECLARE @Name as NVARCHAR(128) <77v8=as5
DECLARE @Owner as NVARCHAR(128) ,=y8[(h
DECLARE @OwnerName as NVARCHAR(128) m'5rzZP
DECLARE curObject CURSOR FOR <R8!fc{`
select 'Name' = name, lBfG#\rdW~
'Owner' = user_name(uid) J]qx4c
from sysobjects $jL+15^N0+
where user_name(uid)=@OldOwner ~A-VgBbU>_
order by name * ;<>@*
OPEN curObject s78V \Vw3
FETCH NEXT FROM curObject INTO @Name, @Owner y<n<uZ;
WHILE(@@FETCH_STATUS=0) ej{7)#
BEGIN $d%NFc&
if @Owner=@OldOwner &-4SA j
begin =\)qUs\z
set @OwnerName = @OldOwner + '.' + rtrim(@Name) #(d/A<
exec sp_changeobjectowner @OwnerName, @NewOwner #{|F2AM
end c4xXsUBQk
-- select @name,@NewOwner,@OldOwner A.(xa+z?
FETCH NEXT FROM curObject INTO @Name, @Owner r_e]sOCb
END IC@-`S#F
close curObject Z*lZl8(`
deallocate curObject 2 [yfo8H
GO mKhlYVn
10、SQL SERVER中直接循环写入数据 h!~u^Z.7<
declare @i int &*!) d"
set @i=1 {ZD'l5jU
while @i<30 iM{UB=C
begin ~OOD#/
insert into test (userid) values(@i) j!hdi-aTU
set @i=@i+1 k{B;J\`E;
end _-bEnF+/0
小记存储过程中经常用到的本周,本月,本年函数 ~Is-^k)y
Dateadd(wk,datediff(wk,0,getdate()),-1) h,)UB1
Dateadd(wk,datediff(wk,0,getdate()),6) n%}Vd
`c
Dateadd(mm,datediff(mm,0,getdate()),0) _,5)
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) ?)'+l
Dateadd(yy,datediff(yy,0,getdate()),0) <[<]+r&*
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) \z)` pno
上面的SQL代码只是一个时间段 ~h6aTN
Dateadd(wk,datediff(wk,0,getdate()),-1) !nyUAZ9 :
Dateadd(wk,datediff(wk,0,getdate()),6) N.qS;%*o{e
就是表示本周时间段. e8$OV4X
下面的SQL的条件部分,就是查询时间段在本周范围内的: D}7G|gX1
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) g)#.|d+
而在存储过程中 ~4[4"Pi>|
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) #J)83
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) R|O."&CAB