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。 l.Iov?e1S
}j;*7x8(
-AWL :<
一、基础 i{vM NI{
1、说明:创建数据库 .-Yhpw>f
CREATE DATABASE database-name Ksr.'
2、说明:删除数据库 ;rC)*=4#
drop database dbname &z8I@^<
3、说明:备份sql server W6:ei.d+NS
--- 创建 备份数据的 device 80DcM9^t8
USE master S2T~7-
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' !36jtKdM
--- 开始 备份 4Hc+F(
BACKUP DATABASE pubs TO testBack q$7SJ.pF
4、说明:创建新表 R9%Um6
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) ~`~mnlN
根据已有的表创建新表: ))JbROBU,
A:create table tab_new like tab_old (使用旧表创建新表) ~\<aj(m(|
B:create table tab_new as select col1,col2... from tab_old definition only 7#wdBB%
5、说明:删除新表 kqdF)Wa am
drop table tabname kwF4I)6
6、说明:增加一个列 1w*DU9f
Alter table tabname add column col type h2<Y*j
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 JL.noV3q$
7、说明:添加主键: Alter table tabname add primary key(col) =wE1j
说明:删除主键: Alter table tabname drop primary key(col) '[V}]Z>-
8、说明:创建索引:create [unique] index idxname on tabname(col....) I*hCIy#;
删除索引:drop index idxname +X#JCLD
注:索引是不可更改的,想更改必须删除重新建。 Kw_> X&GcJ
9、说明:创建视图:create view viewname as select statement [Vzp D 4
删除视图:drop view viewname FtHR.S=u
10、说明:几个简单的基本的sql语句 WCJ$S\#
选择:select * from table1 where 范围 K)=<hL
插入:insert into table1(field1,field2) values(value1,value2) M*6}# ST
删除:delete from table1 where 范围 m$6u K0
更新:update table1 set field1=value1 where 范围
:.u[^_
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! tgz
排序:select * from table1 order by field1,field2 [desc] <Wqk5mR
总数:select count as totalcount from table1 bLSXQStB
求和:select sum(field1) as sumvalue from table1 N{rC#A3
平均:select avg(field1) as avgvalue from table1 8Evon&G59
最大:select max(field1) as maxvalue from table1 ixJ%wnz
最小:select min(field1) as minvalue from table1 ':Avh|q3N
6'E3Q=}d
Teo&V
#ub!
11、说明:几个高级查询运算词 OZ2YflT
NWx.l8G
33/aYy
A: UNION 运算符 g<d#zzP"T
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 A|Z'\D0
B: EXCEPT 运算符 o$disJ
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。 CI%4!K;{
C: INTERSECT 运算符 uv>T8(w
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。 n_ORD@$]
注:使用运算词的几个查询结果行必须是一致的。 p{c+ +P5
12、说明:使用外连接 ?7n(6kmj4Q
A、left outer join: E6
glR
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 m 3k}iIU7
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c hqr V {c
B:right outer join: t.f#_C\
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 mV\QZfoF
C:full outer join: YhpNeP{A
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 gpt98:w:
3JnBKh\n
Dj 0`#~
二、提升 dG{D2~#
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) 9#C hn~ \
法一:select * into b from a where 1<>1 e(t,~(
法二:select top 0 * into b from a 8~q%H1[I\N
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) ;ndsq[k>
insert into b(a, b, c) select d,e,f from b; <Vu/6"DP
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) {Ftz4y)6
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 f/!^QL{
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. &}N=a
4、说明:子查询(表名1:a 表名2:b) YSQB*FBz
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) tp4/c'w;)J
5、说明:显示文章、提交人和最后回复时间 ~k}>CNTr
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b 4&TTPcSt;
6、说明:外连接查询(表名1:a 表名2:b) !4gyrNS
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c UBN^dbP*
7、说明:在线视图查询(表名1:a ) /<J&ZoeJB
select * from (SELECT a,b,c FROM a) T where t.a > 1; qhNY<
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 S4qj}`$
Yv
select * from table1 where time between time1 and time2 F%<hng%k
select a,b,c, from table1 where a not between 数值1 and 数值2 $]H^?
9、说明:in 的使用方法 Hjho!np
select * from table1 where a [not] in ('值1','值2','值4','值6') aDXdr\C6
10、说明:两张关联表,删除主表中已经在副表中没有的信息 1K<4Kz~
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) k Z^}
11、说明:四表联查问题: g8I=s7cnb
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... y:\ ^[y IQ
12、说明:日程安排提前五分钟提醒 vO2I"Y*\
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 C9?R*2L>
13、说明:一条sql 语句搞定数据库分页 !%pY)69gv
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 Ai99:J2k
14、说明:前10条记录 Q2 tM~
select top 10 * form table1 where 范围 HC'k81Q
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) k{fTqKS%h
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) qT
U(]O1
16、说明:包括所有在 TableA 中但不在 TableB和TableC 中的行并消除所有重复行而派生出一个结果表 M@LI(;
(select a from tableA ) except (select a from tableB) except (select a from tableC) !kzC1U
17、说明:随机取出10条数据 86.LkwlqoH
select top 10 * from tablename order by newid() xUp[)B6?:
18、说明:随机选择记录 D'dE!CAUs
select newid() W6=j^nv
19、说明:删除重复记录 QEUr+7[
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) mQVc ZV
20、说明:列出数据库里所有的表名 .Vy*p")"
select name from sysobjects where type='U' }YPW@g
21、说明:列出表里的所有的 b7X-mkF
select name from syscolumns where id=object_id('TableName') YJioR4+q
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 *""JE'wG
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type \M@9#bd
显示结果: @ P[o
type vender pcs N{lj"C]L
电脑 A 1 yS*s[vT
电脑 A 1 n9qO;X4&
光盘 B 2 ppwjr
+
光盘 A 2 Y6_%HYI$
手机 B 3 2(s+?n.N
手机 C 3 IV"OzQONx
23、说明:初始化表table1 ^>?E1J3u
TRUNCATE TABLE table1 s|/m}n
24、说明:选择从10到15的记录 8(.DI/
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc ;=&D_jGf]
TB=KTj
)kMA_\$,
gnAM}
三、技巧 s n|q
EH
1、1=1,1=2的使用,在SQL语句组合时用的较多 $Vu%4kq
"where 1=1" 是表示选择全部 "where 1=2"全部不选, ]e*Zx;6oi
如: 81O\BO.T
if @strWhere !='' u!&w"t61Nd
begin [# X:!xcl
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere /zB;1%m-
end H(eGqVAq,
else M7$ h
begin uxbDRlOS
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' |*~=w J_
end !OM
P]
我们可以直接写成 kG =nDy
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere -uho;
2、收缩数据库 OokBi 02b
--重建索引 buIy+
DBCC REINDEX [G(}`u8w"
DBCC INDEXDEFRAG s_`PPl_D$K
--收缩数据和日志 mLa0BIP
DBCC SHRINKDB &e#>%0aS
DBCC SHRINKFILE #g ;][
3、压缩数据库 [dszz7/L
dbcc shrinkdatabase(dbname) sd (I@
&y
4、转移数据库给新用户以已存在用户权限 -c^/k_n
exec sp_change_users_login 'update_one','newname','oldname' - EwtO4vLJ
go Fx^e%":@ip
5、检查备份集 /F>\-
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' x~7_`=}rO
6、修复数据库 >DHpD?Pm!
ALTER DATABASE [dvbbs] SET SINGLE_USER IEi E6z]L(
GO Z */*P4\
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK f87>ul!*
GO 'rT@r:6fn
ALTER DATABASE [dvbbs] SET MULTI_USER c*O{?b
GO c1v,5c6d j
7、日志清除 1|_8+)i;
SET NOCOUNT ON 0YMmW xV
DECLARE @LogicalFileName sysname, s_(%1/{
@MaxMinutes INT, uYh6q1@"~
@NewSize INT gk%8iT
USE tablename -- 要操作的数据库名 3
cd5g
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 d+9T}? T:*
@MaxMinutes = 10, -- Limit on time allowed to wrap log. ,zCrix
3
@NewSize = 1 -- 你想设定的日志文件的大小(M) u )'l|Y
-- Setup / initialize l\vvM>#S
DECLARE @OriginalSize int njz:7]>e
SELECT @OriginalSize = size Tk9/1C{8
FROM sysfiles M4;A4V=W
WHERE name = @LogicalFileName z0@)@4z!
SELECT 'Original Size of ' + db_name() + ' LOG is ' + In-W,
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + V;b^b5yZ>
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' _g%Wx?K9
FROM sysfiles ELx?ph -9
WHERE name = @LogicalFileName m?Gb5=qo
CREATE TABLE DummyTrans A+JM* eB
(DummyColumn char (8000) not null) ?V6+o`bm
DECLARE @Counter INT, QlbhQkn
@StartTime DATETIME, DYvi1X6
@TruncLog VARCHAR(255) (#w8/@JxF
SELECT @StartTime = GETDATE(), J- %YmUc)
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' GJ >vL
DBCC SHRINKFILE (@LogicalFileName, @NewSize) .x$!Rc}
EXEC (@TruncLog) X%+FM]
-- Wrap the log if necessary. $,vZX u|Qw
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired {H$F!}a
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) !fFmQ\|)4S
AND (@OriginalSize * 8 /1024) > @NewSize "}uPz4
BEGIN -- Outer loop. !Ua74C
SELECT @Counter = 0 R~-r8dWcw
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) "HWl7c3q
BEGIN -- update \wmNeGC2
INSERT DummyTrans VALUES ('Fill Log') %cM2;a=2
DELETE DummyTrans X@,xwsM%tb
SELECT @Counter = @Counter + 1 SE0"25\_G
END '/gw`MJ
EXEC (@TruncLog) T=8>0D^v5
END ulnG|3A9
SELECT 'Final Size of ' + db_name() + ' LOG is ' + O/gBBTB
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + sLx!Do$'
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' |TOz{
FROM sysfiles AHws5#;$6*
WHERE name = @LogicalFileName C[j'0@~V:B
DROP TABLE DummyTrans T)o)%Yv
SET NOCOUNT OFF ;SBM7fwRk
8、说明:更改某个表 @Q"%a`mKH
exec sp_changeobjectowner 'tablename','dbo' ^s@?\v
9、存储更改全部表 ~lx5RTkp
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch C9-90,
@OldOwner as NVARCHAR(128), S.o@95M
@NewOwner as NVARCHAR(128) z3IQPl^
AS aX=
DECLARE @Name as NVARCHAR(128) `sZ/'R6
DECLARE @Owner as NVARCHAR(128) jW6~^>S
DECLARE @OwnerName as NVARCHAR(128) q#v&&]N=
DECLARE curObject CURSOR FOR ~o:lh],~
select 'Name' = name, ojO<sT:by
'Owner' = user_name(uid) P |c6V
from sysobjects A[lkGQtS4
where user_name(uid)=@OldOwner 'C6K\E
order by name dZ UB
OPEN curObject w.qpV]9>
FETCH NEXT FROM curObject INTO @Name, @Owner YaTJKgi"0
WHILE(@@FETCH_STATUS=0) B\2<r5|QG
BEGIN $'}:nwq6x
if @Owner=@OldOwner +
M2|-C
begin V@jR8zv|_
set @OwnerName = @OldOwner + '.' + rtrim(@Name) )W&H{2No
exec sp_changeobjectowner @OwnerName, @NewOwner 4|f I9.
end Rv=(D^F,
-- select @name,@NewOwner,@OldOwner N|eus3\E
FETCH NEXT FROM curObject INTO @Name, @Owner ~4th;#'
END zJ4 2%0g
close curObject JLT^0wBB
deallocate curObject C& 0iWY\a
GO /nEh,<Y)
10、SQL SERVER中直接循环写入数据 E Kks8
declare @i int ;o;P2}zD
set @i=1 ,HXY|fYr
while @i<30 TY"=8}X1
begin 6xSdA;<+]
insert into test (userid) values(@i) `gq@LP"o
set @i=@i+1 Q7`}4c)
end qw[)$icP
小记存储过程中经常用到的本周,本月,本年函数 [Q,E(
s
Dateadd(wk,datediff(wk,0,getdate()),-1) hV_eb6aj}P
Dateadd(wk,datediff(wk,0,getdate()),6) #$(F&>pj
Dateadd(mm,datediff(mm,0,getdate()),0) ^{8r(1,
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) _yTGv-
Dateadd(yy,datediff(yy,0,getdate()),0) `[V]xP%V
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) R;6(2bTN6
上面的SQL代码只是一个时间段 6\(wU?m'/
Dateadd(wk,datediff(wk,0,getdate()),-1) %s~MfK.k
Dateadd(wk,datediff(wk,0,getdate()),6) MyZ@I7Fb,
就是表示本周时间段. ZbJzf]y:6
下面的SQL的条件部分,就是查询时间段在本周范围内的: yG'5u p
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) XW6Ewrm=vT
而在存储过程中 Y5fwmH,a-
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1)
Ch607i=
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) uzL)qH$b