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。 57rP@,vj
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一、基础 r\?*?sL
1、说明:创建数据库 iuRXeiG8
CREATE DATABASE database-name UlR7_
2、说明:删除数据库 2t%)d9r32
drop database dbname Gl(,%~F9i
3、说明:备份sql server 420K fVA
--- 创建 备份数据的 device pw
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USE master A2 rRYzN;
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' B _ >|Mo/
--- 开始 备份 mJ HX
BACKUP DATABASE pubs TO testBack TDFv\y}yc
4、说明:创建新表 y!].l0e2a
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) oz--gA:g
根据已有的表创建新表: oUH\SW8?
A:create table tab_new like tab_old (使用旧表创建新表) 6$Y1[
B:create table tab_new as select col1,col2... from tab_old definition only 9dAsXEWh
5、说明:删除新表 08Gr
drop table tabname ?Z"}RMM)8
6、说明:增加一个列 ]T1"3
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Alter table tabname add column col type GU9`;/
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。 2q>4nN
7、说明:添加主键: Alter table tabname add primary key(col) 0nX5
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说明:删除主键: Alter table tabname drop primary key(col) %"tf`,d~3
8、说明:创建索引:create [unique] index idxname on tabname(col....) gxiJ`.D=
删除索引:drop index idxname 2]l*{l^ Bl
注:索引是不可更改的,想更改必须删除重新建。 v%r! }s
9、说明:创建视图:create view viewname as select statement r iz({
删除视图:drop view viewname IdM;N
10、说明:几个简单的基本的sql语句 >ObpOFb%
选择:select * from table1 where 范围 S<44{
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插入:insert into table1(field1,field2) values(value1,value2) x<" e
删除:delete from table1 where 范围 gNJ\*]SY
更新:update table1 set field1=value1 where 范围 $kdfY'u
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料!
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排序:select * from table1 order by field1,field2 [desc] - >2ej4C
总数:select count as totalcount from table1 [(1O_X(M
求和:select sum(field1) as sumvalue from table1 ;:OJQFu%4
平均:select avg(field1) as avgvalue from table1 M&L" yQA
最大:select max(field1) as maxvalue from table1 ]pb3
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最小:select min(field1) as minvalue from table1 +KZc"0?
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11、说明:几个高级查询运算词 t{ 'QMX
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A: UNION 运算符 y]k`}&-~
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 '7$v@Tvnre
B: EXCEPT 运算符 {.ph)8
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。 4o_1F).\D
C: INTERSECT 运算符 ~96"^%D
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。 ezL*YM8?@
注:使用运算词的几个查询结果行必须是一致的。 HH dc[pJ0D
12、说明:使用外连接 ]l4\/EW6
A、left outer join: ,YH.n>`s+
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。 UV=TU=A\o
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 ls=<c<
B:right outer join: 1i{B47|
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。 &]5<^?3
C:full outer join:
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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。 d(&vIjy
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二、提升 YWTo]DJV
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) sM4N`$Is23
法一:select * into b from a where 1<>1 m<j ^cU#J
法二:select top 0 * into b from a \.{?TB
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) L\"$R":3{d
insert into b(a, b, c) select d,e,f from b; .UJk0%1
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) "5@Y\L
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 cq/)Yff@:
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. =w8*n2
4、说明:子查询(表名1:a 表名2:b) >k:)'*
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) ,5q^/h
5、说明:显示文章、提交人和最后回复时间 t
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select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b t.m
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6、说明:外连接查询(表名1:a 表名2:b) z*FlZLHY
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c Ih{~?(V$
7、说明:在线视图查询(表名1:a ) 2)G ZU
select * from (SELECT a,b,c FROM a) T where t.a > 1; *rWE.4=&
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 0KEytm]
select * from table1 where time between time1 and time2 B]jh$@
select a,b,c, from table1 where a not between 数值1 and 数值2 i
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9、说明:in 的使用方法 ,L`qV
select * from table1 where a [not] in ('值1','值2','值4','值6') c$p1Sovw
10、说明:两张关联表,删除主表中已经在副表中没有的信息 9"/{gf3D
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) H94$Xi"Bd
11、说明:四表联查问题: c45Mv_
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 ..... luV%_[F
12、说明:日程安排提前五分钟提醒 `toSU>:
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 G G7N!eZ
13、说明:一条sql 语句搞定数据库分页 seJc,2Ex
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 4((Z8@iX/
14、说明:前10条记录 X!&=S!}
select top 10 * form table1 where 范围 ;DGp7f#9
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&S
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) n6oVx5/
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 $UKDXQF"
(select a from tableA ) except (select a from tableB) except (select a from tableC) )m?oQ#`m
17、说明:随机取出10条数据 =uD2j9!"7
select top 10 * from tablename order by newid() $WdZAv\_S
18、说明:随机选择记录 lVMAab
select newid()
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19、说明:删除重复记录 +1e*>jE
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) g-6!+>w*>e
20、说明:列出数据库里所有的表名 2-2'c?%
select name from sysobjects where type='U' ?
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21、说明:列出表里的所有的 Oyz=|[^,W
select name from syscolumns where id=object_id('TableName') dNIY`u
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 fE7Kv_N-%
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type vG<Mz?wr
显示结果: Dt8eVWkN ~
type vender pcs Y8Mo .v
电脑 A 1 <&:3|2p
电脑 A 1 \@5W&Be^
光盘 B 2 2H4+D)
光盘 A 2 N:=D@x~]
手机 B 3 d
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手机 C 3 e;Q~P]x
23、说明:初始化表table1 w:pc5N>we0
TRUNCATE TABLE table1 NJn~XCq
24、说明:选择从10到15的记录 gJ2R(YMF
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc RL($h4d9
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三、技巧 !1|f,9C
1、1=1,1=2的使用,在SQL语句组合时用的较多 UGl}=hwKkG
"where 1=1" 是表示选择全部 "where 1=2"全部不选, P^+Og_$
如: O>H4hp
if @strWhere !='' \}Hk`n)Aq
begin b@nbXm]Z
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere S&@~F|
end 6jom6/F 4
else B,}%1+*
begin {?, :M
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' 9'O<d/xj/
end J0^p\mG
我们可以直接写成 AlGD .K
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere ,v(G2`Z
2、收缩数据库 GMd81@7
--重建索引 #~nI^
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DBCC REINDEX vrh}X[JEw'
DBCC INDEXDEFRAG <PXA`]x~
--收缩数据和日志 g`\Vy4w
DBCC SHRINKDB NeUpl./b
DBCC SHRINKFILE %$Mvq&ZZ
3、压缩数据库 M,|o 2'
dbcc shrinkdatabase(dbname) q18dSu
4、转移数据库给新用户以已存在用户权限 OpYq qBf_
exec sp_change_users_login 'update_one','newname','oldname' 2uV=kq nO
go :y0'[LV
5、检查备份集 iQ~cG[6
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' DtyT8kr
6、修复数据库 h1J-AfV
ALTER DATABASE [dvbbs] SET SINGLE_USER .3oFSc`q
GO LTG/gif[u
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK H~&9xtuHN
GO h|_G2p^J+"
ALTER DATABASE [dvbbs] SET MULTI_USER !dGy"-i$h
GO 1 BVivEG
7、日志清除 ;z!~-ByzL
SET NOCOUNT ON 2x'JR yef
DECLARE @LogicalFileName sysname, to+jQ9q8
@MaxMinutes INT, 0G;RMR ':5
@NewSize INT ai#0ZgO
USE tablename -- 要操作的数据库名 ^h=;]vxO
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 65qH
@MaxMinutes = 10, -- Limit on time allowed to wrap log. v='7.A
@NewSize = 1 -- 你想设定的日志文件的大小(M) eRC@b^~
-- Setup / initialize
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DECLARE @OriginalSize int Ix-FJF-
SELECT @OriginalSize = size {U7j
FROM sysfiles X2Y-TET
WHERE name = @LogicalFileName amgYr$)m
SELECT 'Original Size of ' + db_name() + ' LOG is ' + NcRY
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CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + 6SW:'u|90
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' SbrBlP:G
FROM sysfiles liPUK #
WHERE name = @LogicalFileName ^hTq~ "
CREATE TABLE DummyTrans YgrBIul
(DummyColumn char (8000) not null) v&p\r'w
DECLARE @Counter INT, $:F] O$A
@StartTime DATETIME, *m2J$9q
@TruncLog VARCHAR(255) N!^U{;X7/
SELECT @StartTime = GETDATE(), TC"mP!1
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' ?5"~V^L3
DBCC SHRINKFILE (@LogicalFileName, @NewSize) F6YMcdU
EXEC (@TruncLog) sm/l'e
-- Wrap the log if necessary. rn U2EL
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired MvJEX8M
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) X2T)]`@
AND (@OriginalSize * 8 /1024) > @NewSize 5>"-lB &
BEGIN -- Outer loop. Mt<TEr}7Z=
SELECT @Counter = 0 592q`m\
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) f GY. +W_
BEGIN -- update &`0heJ
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INSERT DummyTrans VALUES ('Fill Log') N^CD4l
DELETE DummyTrans /3'>MRzR
SELECT @Counter = @Counter + 1 WZ;f3
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END .u)Po;e`
EXEC (@TruncLog) E.4`aJ@>d
END Q_qc_IcM y
SELECT 'Final Size of ' + db_name() + ' LOG is ' + mp%i(Y"vp
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + o1-Zh!*a*
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' <JDkvpckx.
FROM sysfiles Z3T:R"l;
WHERE name = @LogicalFileName |Zncr9b
DROP TABLE DummyTrans eB^:+h#A_
SET NOCOUNT OFF 5(tOQ%AQ
8、说明:更改某个表 IgQW 5E#
exec sp_changeobjectowner 'tablename','dbo' !$f@j6.
9、存储更改全部表 f
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CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch qP *$wKY,
@OldOwner as NVARCHAR(128), :1s6h%evrT
@NewOwner as NVARCHAR(128) #*1\h=bzmW
AS i{
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DECLARE @Name as NVARCHAR(128) 3QZw
DECLARE @Owner as NVARCHAR(128) $yI!YX&
DECLARE @OwnerName as NVARCHAR(128) ?:~Y%4;
DECLARE curObject CURSOR FOR }vPDCUZ
select 'Name' = name, d* 7 Tjs{\
'Owner' = user_name(uid) C/tn0
from sysobjects -D`*$rp,
where user_name(uid)=@OldOwner TBvv(_
order by name 4Ts5*_
OPEN curObject 83Bp_K2\
FETCH NEXT FROM curObject INTO @Name, @Owner e(,sFhR
WHILE(@@FETCH_STATUS=0) 9=K=gfZ
BEGIN (]0ZxWF
if @Owner=@OldOwner [#$z.BoEo
begin y!)Z ^u
set @OwnerName = @OldOwner + '.' + rtrim(@Name) tA Pqbi$a
exec sp_changeobjectowner @OwnerName, @NewOwner 0r.*7aXu
end DU|0#z=*t5
-- select @name,@NewOwner,@OldOwner A#f@0W:
FETCH NEXT FROM curObject INTO @Name, @Owner Tr-gdX ;
END hd8:| _
close curObject +}J2\!Jw
deallocate curObject w-"o?;)a
GO %, XyhS5[o
10、SQL SERVER中直接循环写入数据 yv[s)c}
declare @i int ^kzw/.I{
set @i=1 W,}HQ
while @i<30 =;i@,{
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begin CT6a
insert into test (userid) values(@i) P}KyT?X:
set @i=@i+1 2~K.m@U}!Z
end K9;pX2^z9
小记存储过程中经常用到的本周,本月,本年函数 8m2-fuJz
Dateadd(wk,datediff(wk,0,getdate()),-1) =pF 6
Dateadd(wk,datediff(wk,0,getdate()),6) #,0%g1
Dateadd(mm,datediff(mm,0,getdate()),0) a)`b;]+9
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) 0' @^PzX
Dateadd(yy,datediff(yy,0,getdate()),0) U(3{6^>Gc
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) ^$4d'
上面的SQL代码只是一个时间段 4M}u_}9
Dateadd(wk,datediff(wk,0,getdate()),-1) F9^8/Z
Dateadd(wk,datediff(wk,0,getdate()),6) N;9@-Tb
就是表示本周时间段. wh<+.Zp
下面的SQL的条件部分,就是查询时间段在本周范围内的: R]0awV1b
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) e3yBB*@
而在存储过程中 w<lHY=z E
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) 3BDAvdJ4.
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) {r#2X1