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。 xdPcsox~
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一、基础 n|WfaJQZ
1、说明:创建数据库 cgyp5\*>+
CREATE DATABASE database-name ny)]GvxI
2、说明:删除数据库 ^EF'TO$
drop database dbname 2Zy_5>~
3、说明:备份sql server WJfES2N
--- 创建 备份数据的 device z5'ZN+
USE master Ejv%,q/T(
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' xOythvO
--- 开始 备份 v,{h:
BACKUP DATABASE pubs TO testBack r088aUO
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4、说明:创建新表 P|N2R5(>T
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 9RH"d[%yc}
根据已有的表创建新表: @D)Z{=>{=5
A:create table tab_new like tab_old (使用旧表创建新表) [& ^RP,N~
B:create table tab_new as select col1,col2... from tab_old definition only % #u.J
5、说明:删除新表 |m)kN2w
drop table tabname ,9d9_c.T
6、说明:增加一个列 [F+,YV%t
Alter table tabname add column col type F?9SiX[\
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。 eX"''PA
7、说明:添加主键: Alter table tabname add primary key(col) #n3ykzoqIX
说明:删除主键: Alter table tabname drop primary key(col) GX
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8、说明:创建索引:create [unique] index idxname on tabname(col....) nU2V]-qY
删除索引:drop index idxname -p`L%xj\
注:索引是不可更改的,想更改必须删除重新建。 JEhm1T
9、说明:创建视图:create view viewname as select statement yoQ\lk
删除视图:drop view viewname w~|1Wd<v
10、说明:几个简单的基本的sql语句 <*<U!J-i
选择:select * from table1 where 范围 6V1:qp/6
插入:insert into table1(field1,field2) values(value1,value2) )T1iN(Z
删除:delete from table1 where 范围 yS!(Ap
更新:update table1 set field1=value1 where 范围 io.]'">
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! dY!u)M;~~
排序:select * from table1 order by field1,field2 [desc] "UG
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总数:select count as totalcount from table1 o_f-GO
求和:select sum(field1) as sumvalue from table1 e4\dpvL
平均:select avg(field1) as avgvalue from table1 "$| Zr
最大:select max(field1) as maxvalue from table1 +BL{@,zr
最小:select min(field1) as minvalue from table1 ]a?bzOr,
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11、说明:几个高级查询运算词 FJ54S
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A: UNION 运算符 =sgdkAYwP
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。 lr~0pL
B: EXCEPT 运算符 .tnkT;T
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。 Y3Oz'%B
C: INTERSECT 运算符 IRW^ok.'b!
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。 w5,Mb
注:使用运算词的几个查询结果行必须是一致的。 8 lT{1ro
12、说明:使用外连接 T%IK/"N|+
A、left outer join: e,gyQjJR
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。 ,<`)>2 '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 Ak@Dyi?p
B:right outer join: Q@S-f:!
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。 V
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C:full outer join: @S^ASDuQU7
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。 Bp?
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二、提升 N|usFqCNk^
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) -_N)E ))G
法一:select * into b from a where 1<>1 nw6pV%
法二:select top 0 * into b from a 5(m(xo6
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) p3(2?UO!
insert into b(a, b, c) select d,e,f from b; cU.9}-)
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's~>up&
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 aZS7sV28
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. P8Qyhc
4、说明:子查询(表名1:a 表名2:b) u<xo/=Z
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) GVGlVAo|@
5、说明:显示文章、提交人和最后回复时间 >ut" OL9J
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b % Zjdl
6、说明:外连接查询(表名1:a 表名2:b) #5} wuj%5
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c Vvp[P>
7、说明:在线视图查询(表名1:a ) XvTCK>1
select * from (SELECT a,b,c FROM a) T where t.a > 1; zp}eLm:=d
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 U8$4
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select * from table1 where time between time1 and time2 > L2HET
select a,b,c, from table1 where a not between 数值1 and 数值2 cVnJ^*Z
9、说明:in 的使用方法 ]=pR
select * from table1 where a [not] in ('值1','值2','值4','值6') zP\7S}p7%
10、说明:两张关联表,删除主表中已经在副表中没有的信息 2,q}Nq
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) PNs~[
11、说明:四表联查问题: =q7Z qP
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... SRIA*M.B}
12、说明:日程安排提前五分钟提醒 ,f3pqi9|
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 r!1D*v5&:
13、说明:一条sql 语句搞定数据库分页 46@{5)Tq
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 k <iTjI*N
14、说明:前10条记录 s$ENFp7P
select top 10 * form table1 where 范围 :KJ pk:<
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.) Rhc-q|Lz8
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) q[q?hQ/b
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 N["W Ir
(select a from tableA ) except (select a from tableB) except (select a from tableC) Hmt^h(*/2
17、说明:随机取出10条数据 :}8Z@H!KkY
select top 10 * from tablename order by newid() H %JaZ?(
18、说明:随机选择记录 {9Y+.46S
select newid() i<kD
19、说明:删除重复记录 #'D"
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Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) 2WX7nK;I
20、说明:列出数据库里所有的表名 Z>c3
select name from sysobjects where type='U' . o7m!
21、说明:列出表里的所有的 B~]5$-
select name from syscolumns where id=object_id('TableName') O/AaYA&
22、说明:列示type、vender、pcs字段,以type字段排列,case可以方便地实现多重选择,类似select 中的case。 3s\.cG?`r
select type,sum(case vender when 'A' then pcs else 0 end),sum(case vender when 'C' then pcs else 0 end),sum(case vender when 'B' then pcs else 0 end) FROM tablename group by type 00v&lQBW
显示结果: f`9
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type vender pcs x-OA([;/
电脑 A 1 4#x5MM
电脑 A 1 `ps)0!L
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光盘 B 2 X[`bMa7IB(
光盘 A 2 UcBe'r}G
手机 B 3 wW>zgTG
手机 C 3 HEA#bd\
23、说明:初始化表table1 Gj"7s8(/K|
TRUNCATE TABLE table1 kt`nbm|aw
24、说明:选择从10到15的记录 -F'b8:m
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc Y<1QY?1sd
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三、技巧 5N%93{L
1、1=1,1=2的使用,在SQL语句组合时用的较多 u[nyW3MZ
"where 1=1" 是表示选择全部 "where 1=2"全部不选, 8} =JKR^cK
如: @d Jr/6Yx
if @strWhere !='' GKN%Tv:D_
begin
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set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere q _-7i
end :'#TCDlOb
else afYc\-"
begin nX$XL=6mJ&
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' Neg,qOt
end ': N51kC
我们可以直接写成 vAyFm dJ^
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere m(pE5B(
2、收缩数据库 h/~n\0,J/
--重建索引 I\YV des#
DBCC REINDEX D9j3Xu
DBCC INDEXDEFRAG |V<h=D5W
--收缩数据和日志 ^Z:~91Tv-_
DBCC SHRINKDB ]`Oo%$Ue
DBCC SHRINKFILE ]XI*Wsn
3、压缩数据库 L!=QR8?@E
dbcc shrinkdatabase(dbname) ^^5&QSB:'
4、转移数据库给新用户以已存在用户权限 g!-,]
exec sp_change_users_login 'update_one','newname','oldname' m!<\WN6g
go 9K9DF1SOa
5、检查备份集 ]c! ;L5
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' Yo[;W
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6、修复数据库 jQ:OKh<Y
ALTER DATABASE [dvbbs] SET SINGLE_USER N^3N[lD{
GO ,yd?gP-O
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK "HPB!)C8(
GO `ho1nY$)CE
ALTER DATABASE [dvbbs] SET MULTI_USER ~8lwe*lNV
GO s8}@=]aA
7、日志清除 H,b5C_D29
SET NOCOUNT ON {)-aSywe
DECLARE @LogicalFileName sysname, k+ze74_"
@MaxMinutes INT, EVoEszR
@NewSize INT rwGKfoKI
USE tablename -- 要操作的数据库名 Hla0 5N' 4
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 D:erBMKv,
@MaxMinutes = 10, -- Limit on time allowed to wrap log. b,CaWg
@NewSize = 1 -- 你想设定的日志文件的大小(M) P>Ez'C
-- Setup / initialize %Ah^E$&n2
DECLARE @OriginalSize int Zl*X?5u
SELECT @OriginalSize = size xP [n
FROM sysfiles B'fb^n<
WHERE name = @LogicalFileName t25,0<iW
SELECT 'Original Size of ' + db_name() + ' LOG is ' + y~FV2$
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + P'`r
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' -]QD|w3dp
FROM sysfiles 0zi~p>*nJC
WHERE name = @LogicalFileName DCZ\6WY1G)
CREATE TABLE DummyTrans L31HGH2l
(DummyColumn char (8000) not null) rnF/H=I/
DECLARE @Counter INT, <WcR,d
@StartTime DATETIME, \Cii1\R=
@TruncLog VARCHAR(255) 9^j &VmF
SELECT @StartTime = GETDATE(), )BwjZMJ.N
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' /AW=5Ck- #
DBCC SHRINKFILE (@LogicalFileName, @NewSize) $g
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EXEC (@TruncLog) nX=$EQiH
-- Wrap the log if necessary. S;)w.
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired Qc pm!
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName)
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AND (@OriginalSize * 8 /1024) > @NewSize Iu <?&9t
BEGIN -- Outer loop. CY"/uSB
SELECT @Counter = 0 JhLgCnm
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) s{$(*_
BEGIN -- update =17t-
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INSERT DummyTrans VALUES ('Fill Log') sIxTG y.
DELETE DummyTrans +1D+]*t_?[
SELECT @Counter = @Counter + 1 iB498t
END M#8uv-L
EXEC (@TruncLog) sashzVwJ-=
END |g//g\dd
SELECT 'Final Size of ' + db_name() + ' LOG is ' + v+X)Qmzf~
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + ~FN9 [aJF+
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' xjVS
FROM sysfiles D`$hPYK|_
WHERE name = @LogicalFileName XR;eY:89
DROP TABLE DummyTrans lQe%Yh
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SET NOCOUNT OFF 7BJzMlJ1Y
8、说明:更改某个表 pNKhc#-w
exec sp_changeobjectowner 'tablename','dbo' m+Rv+_R
9、存储更改全部表
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CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch @]ytla>d
@OldOwner as NVARCHAR(128), |563D#?cR
@NewOwner as NVARCHAR(128) <kx&w(=
AS 7*?}:
DECLARE @Name as NVARCHAR(128) CW,Wx: Y
DECLARE @Owner as NVARCHAR(128) U4b0*` o
DECLARE @OwnerName as NVARCHAR(128) L:i-BI`J
DECLARE curObject CURSOR FOR ~1>.A(,=z
select 'Name' = name, id1s3b;
'Owner' = user_name(uid) Yo|,]X>/
from sysobjects SN1}xR$
where user_name(uid)=@OldOwner `pGa~!vl
order by name <y?r!l=Am
OPEN curObject ;N0~;I
FETCH NEXT FROM curObject INTO @Name, @Owner vy\RcP
WHILE(@@FETCH_STATUS=0) U
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BEGIN ,f[>L|?e
if @Owner=@OldOwner [O?z@)dx
begin
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set @OwnerName = @OldOwner + '.' + rtrim(@Name) BEre*J
exec sp_changeobjectowner @OwnerName, @NewOwner 61)-cVC
end (adyZ/j
-- select @name,@NewOwner,@OldOwner ;{KV /<3
FETCH NEXT FROM curObject INTO @Name, @Owner u[DfzH
END f)^_|8
close curObject \uaJ@{Vug
deallocate curObject 4X+ifZO
GO V{:A3C41
10、SQL SERVER中直接循环写入数据 5'X ]k@m_
declare @i int mqSQL}vR
set @i=1 _s .G
while @i<30 @NNq z
begin JYW)uJ
insert into test (userid) values(@i) A m>cd;
set @i=@i+1 @CZT
end 3%(N[&LU
小记存储过程中经常用到的本周,本月,本年函数 6er-{.L=
Dateadd(wk,datediff(wk,0,getdate()),-1) i5CK*"$Q
Dateadd(wk,datediff(wk,0,getdate()),6) WZ*ws[dVI
Dateadd(mm,datediff(mm,0,getdate()),0) "saUai4z
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) x6e}( &p*
Dateadd(yy,datediff(yy,0,getdate()),0) 9*{[buZX
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) &3TEfvz
上面的SQL代码只是一个时间段 6y9t(m
Dateadd(wk,datediff(wk,0,getdate()),-1) !3*(N8_|#
Dateadd(wk,datediff(wk,0,getdate()),6) U8LtG/
就是表示本周时间段. iC98_o_9
下面的SQL的条件部分,就是查询时间段在本周范围内的: ck.w
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Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) SBIj<Yy]
而在存储过程中 .U?'i<
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) }Du}c3
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) ]Zyur`