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。 4V+bE$Wu
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一、基础 fUT[tkb/!
1、说明:创建数据库 CFtQPTw
CREATE DATABASE database-name Sc<dxY@w7-
2、说明:删除数据库 384n1?
drop database dbname o4Q?K.9c
3、说明:备份sql server QYH-"-)
--- 创建 备份数据的 device \nl(tU#j
USE master ].d2C J'
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' @^,q/%;
--- 开始 备份 >ahDc!Jyu
BACKUP DATABASE pubs TO testBack Y
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4、说明:创建新表 IskL$Y ^
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) \]X.f&u
根据已有的表创建新表: ;4F6
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A:create table tab_new like tab_old (使用旧表创建新表) R/hf"E1
B:create table tab_new as select col1,col2... from tab_old definition only r4yz{^G
5、说明:删除新表 E]V,
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drop table tabname (,|,j(=]
6、说明:增加一个列 W`>|OiuF
Alter table tabname add column col type z*.AuEK?
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。 aKI"<%PNn
7、说明:添加主键: Alter table tabname add primary key(col) y=3 dGOFB
说明:删除主键: Alter table tabname drop primary key(col) 1/DtF
8、说明:创建索引:create [unique] index idxname on tabname(col....) j\y;~
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删除索引:drop index idxname Ymut]`dX
注:索引是不可更改的,想更改必须删除重新建。 ^z?b6kTC
9、说明:创建视图:create view viewname as select statement !cW rB9
删除视图:drop view viewname 3?93Pj3oPt
10、说明:几个简单的基本的sql语句 3[m~-8
选择:select * from table1 where 范围 @r"\bBi
插入:insert into table1(field1,field2) values(value1,value2) g4?2'G5m?
删除:delete from table1 where 范围 Oa[
更新:update table1 set field1=value1 where 范围 %|-N{> wKy
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! |XyX%5p*
排序:select * from table1 order by field1,field2 [desc] C=?S
总数:select count as totalcount from table1 X 4;U4pU#
求和:select sum(field1) as sumvalue from table1 (J:+'u
平均:select avg(field1) as avgvalue from table1 ]!hjKu"
最大:select max(field1) as maxvalue from table1 o_:v?Y>0
最小:select min(field1) as minvalue from table1 )%(ZFn}
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11、说明:几个高级查询运算词 !:(+#
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A: UNION 运算符 P\U<,f
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。 qt8Y3:=8l
B: EXCEPT 运算符 *!5CL'
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。 MAa9JA8kw)
C: INTERSECT 运算符 @6
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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。 DB vM.'b$
注:使用运算词的几个查询结果行必须是一致的。 Q):#6|u+
12、说明:使用外连接 g"-j/ c
A、left outer join: K@.5
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。 ]7HR
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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 s:T%,xS
B:right outer join: !3b& S4
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。 -&/?&{Q0
C:full outer join: 85<k'>~L
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。 ZrN(Mp
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二、提升 ~
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1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) H%_^Gy8f
法一:select * into b from a where 1<>1 6 @f>
法二:select top 0 * into b from a vs@d)$N
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) .S` q2C\
insert into b(a, b, c) select d,e,f from b; *xnZTj:
3、说明:跨数据库之间表的拷贝(具体数据使用绝对路径) (Access可用) wE
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insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 T3w%y`K
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. Xaz "!
4、说明:子查询(表名1:a 表名2:b) =*UK!y?n
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) g]~vZj
5、说明:显示文章、提交人和最后回复时间 VG5+u,U6>
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b (UkP AE
6、说明:外连接查询(表名1:a 表名2:b) hh;kBv07o
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c u>>|ZPe
7、说明:在线视图查询(表名1:a ) a%#UF@I
select * from (SELECT a,b,c FROM a) T where t.a > 1; {gD ED
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 M9"Bx/
select * from table1 where time between time1 and time2 U9
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select a,b,c, from table1 where a not between 数值1 and 数值2 H,>
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9、说明:in 的使用方法 J*@ pM
select * from table1 where a [not] in ('值1','值2','值4','值6') J""Cgf
10、说明:两张关联表,删除主表中已经在副表中没有的信息 lm`*x=x
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) !j!w$
11、说明:四表联查问题: Y9.3`VX
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 ..... 2Zu9?
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12、说明:日程安排提前五分钟提醒 dL42)HP5
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 {"o9pIh{~
13、说明:一条sql 语句搞定数据库分页 *@rA7zPFf
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 ]d*9@+Iu
14、说明:前10条记录 1}VaBsEV
select top 10 * form table1 where 范围 yP"2.9\erH
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.) 5/.W-Q\pl}
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) GcO2oq
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 `KQx#c>'
(select a from tableA ) except (select a from tableB) except (select a from tableC) jg$qp%7i%
17、说明:随机取出10条数据 Dk
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select top 10 * from tablename order by newid() Ejk;(rxI
18、说明:随机选择记录 /&gg].&2?
select newid() ~WA@YjQ]
19、说明:删除重复记录 tZ]gVgZg
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) rPk|2l,E,3
20、说明:列出数据库里所有的表名 *Y> w0k
select name from sysobjects where type='U' QK_5gD`$a,
21、说明:列出表里的所有的 jKUEs75]
select name from syscolumns where id=object_id('TableName') =~:IiK/#
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。 n|5\Q
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 Y3 $jNuV
显示结果: fU6YJs.H^8
type vender pcs x`6MAZ
电脑 A 1 s&73g0$$
电脑 A 1 BlJiHz!
光盘 B 2 p4T$(]7
光盘 A 2 -y.cy'$f
手机 B 3 R ]Ev=V'U
手机 C 3 Jv}
23、说明:初始化表table1 ^4sfVpD2!
TRUNCATE TABLE table1 G)vNMl
24、说明:选择从10到15的记录 s^u Y
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 MCN>3/81
1、1=1,1=2的使用,在SQL语句组合时用的较多 FJvY`zqB
"where 1=1" 是表示选择全部 "where 1=2"全部不选, HXq']+iC
如: 4 OPY
if @strWhere !='' *'((_NZ>
begin mCO1,?
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere ox-m)z `7
end P~ObxY|
else aUw-P{zp%
begin O3 sV)
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' (?e%w}
end ,YD7p= PY
我们可以直接写成 kjYM&q
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere Dg&6@c|
2、收缩数据库 2^r~->
--重建索引 5FOMh"!z\
DBCC REINDEX bZxN]6_
DBCC INDEXDEFRAG sK2N3B&6
--收缩数据和日志 -6[DQB
DBCC SHRINKDB
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DBCC SHRINKFILE R"W}\0k
3、压缩数据库
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dbcc shrinkdatabase(dbname)
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4、转移数据库给新用户以已存在用户权限 REW[`MBQ
exec sp_change_users_login 'update_one','newname','oldname' 2U)n^
go ;,bgJgK
5、检查备份集 oC5h-4~
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' @7 Ry{,A
6、修复数据库 _a$qsY
ALTER DATABASE [dvbbs] SET SINGLE_USER ^xe+(83S2?
GO wI@87&
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK @R&d<^I&M
GO 'AA9F$Dz
ALTER DATABASE [dvbbs] SET MULTI_USER Gxw1P@<F:
GO =RB
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7、日志清除 n&[CTOV
SET NOCOUNT ON vPDw22L;'
DECLARE @LogicalFileName sysname, 5cPyi/
@MaxMinutes INT, P%2v(
@NewSize INT 5%}e j)@
USE tablename -- 要操作的数据库名 d{YvdN9d
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 R'Jrbe|
@MaxMinutes = 10, -- Limit on time allowed to wrap log. S;4:`?s=i
@NewSize = 1 -- 你想设定的日志文件的大小(M) ]oP1c-GEk
-- Setup / initialize !|[rh,e]
DECLARE @OriginalSize int ;1(^H:7T
SELECT @OriginalSize = size GD4S/fn3
FROM sysfiles NW1 Jr/
WHERE name = @LogicalFileName Y-ao
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SELECT 'Original Size of ' + db_name() + ' LOG is ' + UGAV"0
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + t6"%u3W8M
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' C:B 7%<
FROM sysfiles |nNcV~%~
WHERE name = @LogicalFileName Sf?;j{?G
CREATE TABLE DummyTrans Qu|CXUk
(DummyColumn char (8000) not null) =F+v+zP7P
DECLARE @Counter INT, /h>g-zb
@StartTime DATETIME, z:\9t[e4
@TruncLog VARCHAR(255) p@jw)xI
SELECT @StartTime = GETDATE(), ed6@o4D/kf
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' re*}a)iL
DBCC SHRINKFILE (@LogicalFileName, @NewSize) =Dn<DV
EXEC (@TruncLog) -Q20af-
-- Wrap the log if necessary. ea=E/HR-
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired _,drOF|e
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) hU$aZ
AND (@OriginalSize * 8 /1024) > @NewSize n\+c3
BEGIN -- Outer loop. afrF%!
SELECT @Counter = 0 R1zt6oY
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) #Y=^4 U`
BEGIN -- update gH//@`6
INSERT DummyTrans VALUES ('Fill Log') neFwxS?
DELETE DummyTrans oxxuw
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SELECT @Counter = @Counter + 1 bv4umL /
END {;{U@Z
EXEC (@TruncLog) rI>x'0Go*
END YY;<y%:8Z
SELECT 'Final Size of ' + db_name() + ' LOG is ' + N`W[Q>n
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + kyHli~Nr"
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' JV~
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FROM sysfiles M`Q$-#E:
WHERE name = @LogicalFileName 9tHK_),9
DROP TABLE DummyTrans ^`cv6;)
SET NOCOUNT OFF ~$y"Ldrp
8、说明:更改某个表 AQ)gj$
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exec sp_changeobjectowner 'tablename','dbo' 6=f)3!=
9、存储更改全部表 `\( ?^]WLa
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch cO
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@OldOwner as NVARCHAR(128), .I^4Fc}&4
@NewOwner as NVARCHAR(128) :-RB< Lj
AS !+SL=xy!{
DECLARE @Name as NVARCHAR(128) Ro<779.Gn\
DECLARE @Owner as NVARCHAR(128) \B#tB?rA
DECLARE @OwnerName as NVARCHAR(128) &l+Qn'N
DECLARE curObject CURSOR FOR 0x<ASfka
select 'Name' = name, a&'9[9E1
'Owner' = user_name(uid) |.)LZP,
from sysobjects :qE.(k1@5
where user_name(uid)=@OldOwner $9G&
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order by name PMAz[w,R~
OPEN curObject UBwl2Di
FETCH NEXT FROM curObject INTO @Name, @Owner f./K/
WHILE(@@FETCH_STATUS=0) ZVXPp-M
BEGIN H_?rbz} o
if @Owner=@OldOwner \HO)ss)"
begin GxhE5f;
set @OwnerName = @OldOwner + '.' + rtrim(@Name) |u>V>
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exec sp_changeobjectowner @OwnerName, @NewOwner v.]{b8RR
end $5XAS
-- select @name,@NewOwner,@OldOwner ]W3_]N 3
FETCH NEXT FROM curObject INTO @Name, @Owner *q6XK_
END 'x%gJi#
close curObject =E2 a#Vd
deallocate curObject FtTq*[a
GO E^)FnXe5
10、SQL SERVER中直接循环写入数据 'iW
declare @i int .?u<|4jE6
set @i=1 iYr)Ao5X
while @i<30 lrE"phYk
begin =NY;#Jjn
insert into test (userid) values(@i) RiTL(Yx
set @i=@i+1 K$Bv4_|x
end !Q>xVlPVu
小记存储过程中经常用到的本周,本月,本年函数 { {\oC$
Dateadd(wk,datediff(wk,0,getdate()),-1) $UzSPhv[
Dateadd(wk,datediff(wk,0,getdate()),6) KPToyCyR1
Dateadd(mm,datediff(mm,0,getdate()),0) A}lxJ5h0
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) 'pt(
Dateadd(yy,datediff(yy,0,getdate()),0) }R;}d(C`
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) 1WtE ]
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上面的SQL代码只是一个时间段 AGFA;X
Dateadd(wk,datediff(wk,0,getdate()),-1) 54p{J
Dateadd(wk,datediff(wk,0,getdate()),6) f7*Qa!!2p]
就是表示本周时间段. :u7BCV|yr
下面的SQL的条件部分,就是查询时间段在本周范围内的: =K:[26
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) $z_yx
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而在存储过程中 :aOR@])>o
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) ^=x /:0
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) ;n't:yQW