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。 #bH_Dg5I
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一、基础 >J9oH=S6
1、说明:创建数据库 }e2VY
CREATE DATABASE database-name vS\Nd1~ ?
2、说明:删除数据库 SAYLG
drop database dbname ZJPmR/OV_
3、说明:备份sql server HpZ1xT
--- 创建 备份数据的 device N@ \&1I`c$
USE master EU7|,>a
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' V!v:]E
--- 开始 备份 f| _u7"OX
BACKUP DATABASE pubs TO testBack 5"XC$?I<}
4、说明:创建新表 PHOP%hI$
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 0k)rc$eDF+
根据已有的表创建新表: Q7Iw[=;\
A:create table tab_new like tab_old (使用旧表创建新表) fGhn+8VfX
B:create table tab_new as select col1,col2... from tab_old definition only v6.t{6zYgY
5、说明:删除新表 M?m,EQh.
drop table tabname ^=>Tk$ _2
6、说明:增加一个列 ?POUtRN
Alter table tabname add column col type $odso;Hn
注:列增加后将不能删除。DB2中列加上后数据类型也不能改变,唯一能改变的是增加varchar类型的长度。 g0R~&AN!g
7、说明:添加主键: Alter table tabname add primary key(col) CI353-`
说明:删除主键: Alter table tabname drop primary key(col) ls@i".[
8、说明:创建索引:create [unique] index idxname on tabname(col....) '3zc|eJt&
删除索引:drop index idxname A,sr[Pa@
注:索引是不可更改的,想更改必须删除重新建。 .<@8gNm3
9、说明:创建视图:create view viewname as select statement .X# `k
删除视图:drop view viewname 1-lu\"H`
10、说明:几个简单的基本的sql语句 Pj}66.
选择:select * from table1 where 范围 dXF^(y]l
插入:insert into table1(field1,field2) values(value1,value2) Tg!m`9s+
删除:delete from table1 where 范围 93Co}@Y;Y+
更新:update table1 set field1=value1 where 范围 pe^u$YE
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! If\fLhM
排序:select * from table1 order by field1,field2 [desc] 89r DyRJ;
总数:select count as totalcount from table1 ^R:cd8+?%
求和:select sum(field1) as sumvalue from table1 9eH$XYy
平均:select avg(field1) as avgvalue from table1 bv&;R
最大:select max(field1) as maxvalue from table1 E?_Z`*h
最小:select min(field1) as minvalue from table1 dC RyOid$
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11、说明:几个高级查询运算词 8F'x=lIO
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A: UNION 运算符 AvfNwE
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。 9I4K}R
B: EXCEPT 运算符 ]*AR,0N&
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。 Mnscb
C: INTERSECT 运算符 MdvcnaCG
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。 :Of^xj>A
注:使用运算词的几个查询结果行必须是一致的。 +F^^c2E
12、说明:使用外连接 =>_\fNy
A、left outer join: .>WxDQIo
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。 #w' kV#
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 >k (C
B:right outer join: HhvdqvIEG
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。 CLUW!F
C:full outer join: ]"?)Z
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。 ]@phF _
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二、提升 EwvoQ$#jv
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) R}!:'^
法一:select * into b from a where 1<>1 #T'{ n1AI
法二:select top 0 * into b from a E&[{4Ml
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) De'_SD|=
insert into b(a, b, c) select d,e,f from b; L6|oyf
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) ^SF&=NpV
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 ]SLP}Jwy
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. toBHkiuD
4、说明:子查询(表名1:a 表名2:b) E?
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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) \RC'XKQ*n
5、说明:显示文章、提交人和最后回复时间 5Ou`z5S\k
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b *^VRGfpb
6、说明:外连接查询(表名1:a 表名2:b) H _zo1AW
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c P&*2pX:
7、说明:在线视图查询(表名1:a ) SC)g^E#
select * from (SELECT a,b,c FROM a) T where t.a > 1; <^5Z:n!q
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 %D\[*
select * from table1 where time between time1 and time2 |}Nn!Sj>#;
select a,b,c, from table1 where a not between 数值1 and 数值2 d,B:kE0Y
9、说明:in 的使用方法 h7lDHIQf
select * from table1 where a [not] in ('值1','值2','值4','值6') BHU6t<G
10、说明:两张关联表,删除主表中已经在副表中没有的信息 KUlp"{a`,K
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) 3sy (vC
11、说明:四表联查问题: {Tq_7,8
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 ..... V{/?FO?E
12、说明:日程安排提前五分钟提醒 a%/9v"}
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 s@K4u^$A
13、说明:一条sql 语句搞定数据库分页 8
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select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 \o*5
14、说明:前10条记录 |EX(8y
select top 10 * form table1 where 范围 gd`!tRcNY
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) o$jLzE"
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) Y)* #)f
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 :VRNs
(select a from tableA ) except (select a from tableB) except (select a from tableC) P3+5?.p.
17、说明:随机取出10条数据 k@ RDvn
select top 10 * from tablename order by newid() v3~? ;f,l
18、说明:随机选择记录 P}n_IV*@
select newid() Jh,]r?Bd
19、说明:删除重复记录 Z>:NPZODf
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) Ug>~Rq]
20、说明:列出数据库里所有的表名 x[~b2o
select name from sysobjects where type='U'
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21、说明:列出表里的所有的 =.Pw`.
select name from syscolumns where id=object_id('TableName') %[Wh [zZy
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。 B~MU^|v
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 n'n/Tu
显示结果: @\0ez<.p}
type vender pcs #rMlI3;
电脑 A 1 `2("gUCm
电脑 A 1 mqD}BOif
光盘 B 2 _S<3\%(0
光盘 A 2 4;e5H_}Oo
手机 B 3 y-'$(x
手机 C 3 EN<F# Y3E
23、说明:初始化表table1 DE}K~}sbd
TRUNCATE TABLE table1 0L2 F[TN
24、说明:选择从10到15的记录 S 6@u@C
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc k:t]s_`<
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三、技巧 rK' L6o
1、1=1,1=2的使用,在SQL语句组合时用的较多 _<n~n]%
"where 1=1" 是表示选择全部 "where 1=2"全部不选, vYwYQG
如: '\l"
if @strWhere !='' q6McG HT
begin W#9BNKL
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere kyR:[+je
end M'?,] an
else \tf<B\oa
begin q<xCb%#Jl
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' orzZ{87
end p|X"@kuseO
我们可以直接写成 9&-dTayIz
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere |s7s6k)mm
2、收缩数据库 bn|I>e
--重建索引 >:74%D0UF
DBCC REINDEX zGb|) A~,
DBCC INDEXDEFRAG ,?J!
--收缩数据和日志 |^&b8
DBCC SHRINKDB ?&8^&brwG
DBCC SHRINKFILE {f Py=,>Nb
3、压缩数据库 f(>p=%=O
dbcc shrinkdatabase(dbname) J{.{f
4、转移数据库给新用户以已存在用户权限 0.`/X66;V
exec sp_change_users_login 'update_one','newname','oldname' Z;ht
go Q- cFtu-w
5、检查备份集 m|SUV
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' %0S3V[4I
6、修复数据库 D$w6V
ALTER DATABASE [dvbbs] SET SINGLE_USER b o6d)Q
GO VQc_|z_s
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK [;n9:Qxf
GO = 6j&4p
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ALTER DATABASE [dvbbs] SET MULTI_USER lUOF4U&r
GO Y+kfBvxyf
7、日志清除 qk%;on&`
SET NOCOUNT ON ;,hwZZA
DECLARE @LogicalFileName sysname, 9g9HlB&Ze
@MaxMinutes INT, hr#M-K
@NewSize INT {BP{C=p
USE tablename -- 要操作的数据库名 cXA
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SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 Eq% }
@MaxMinutes = 10, -- Limit on time allowed to wrap log. \{Y 7FC~
@NewSize = 1 -- 你想设定的日志文件的大小(M) ;"a=gr
-- Setup / initialize E(*0jAvO[z
DECLARE @OriginalSize int J?*1*h
SELECT @OriginalSize = size DwM)r7<Ex
FROM sysfiles U\g/ 2dM
WHERE name = @LogicalFileName 2Z+Wu3#
SELECT 'Original Size of ' + db_name() + ' LOG is ' + ]&o$b ]
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + z 9vInf@M
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' `LrHKb
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FROM sysfiles X:A^<L
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WHERE name = @LogicalFileName 2]z8:a
CREATE TABLE DummyTrans bZ dNibN
(DummyColumn char (8000) not null) tZ]?^_Y1
DECLARE @Counter INT, f/ U`
@StartTime DATETIME, W\>fh&!)
@TruncLog VARCHAR(255) Cz9xZA{[M
SELECT @StartTime = GETDATE(), mUNn%E:7@{
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' q_MPju&*
DBCC SHRINKFILE (@LogicalFileName, @NewSize) [8Y:65
EXEC (@TruncLog) _'#n6^Us<
-- Wrap the log if necessary. ayn) 5q/z
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired tP:lP#9
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) BOX{]EOj
AND (@OriginalSize * 8 /1024) > @NewSize T(#J_Y
BEGIN -- Outer loop. hwPw]Ln/
SELECT @Counter = 0 RFi
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WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) ?qmRbDI
BEGIN -- update &xU[E!2H%
INSERT DummyTrans VALUES ('Fill Log') S-a]j;U
DELETE DummyTrans YDIG,%uv
SELECT @Counter = @Counter + 1 RF`.xQ26=
END T]^62(So
EXEC (@TruncLog) Fe# 1
END 9>=;FY
SELECT 'Final Size of ' + db_name() + ' LOG is ' + 9"N~yKa`"K
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + +G$4pt|=
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' >f|||H}Snw
FROM sysfiles P9/q|>F
WHERE name = @LogicalFileName `}D,5^9]
DROP TABLE DummyTrans |'e^QpU5
SET NOCOUNT OFF Q{O+
8、说明:更改某个表 l#g\X'bK
exec sp_changeobjectowner 'tablename','dbo' ;nI] !g:
9、存储更改全部表 !eGC6o}f
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch ]P9l jwR
@OldOwner as NVARCHAR(128), mu\6z_e
@NewOwner as NVARCHAR(128) +=>,Pto<
AS u]g%@3Pn
DECLARE @Name as NVARCHAR(128) ~Z -Vs
DECLARE @Owner as NVARCHAR(128) t*=CZE -
DECLARE @OwnerName as NVARCHAR(128) y|jl[pyg)
DECLARE curObject CURSOR FOR m~w[~flgZ
select 'Name' = name, SU MrFd~
'Owner' = user_name(uid) =h-U
from sysobjects h!M
where user_name(uid)=@OldOwner Bm:98? [
order by name On8v//=&
OPEN curObject
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FETCH NEXT FROM curObject INTO @Name, @Owner Vouvr<43o
WHILE(@@FETCH_STATUS=0) oro$wFxJO
BEGIN pD8+ 4;A
if @Owner=@OldOwner ! :Y:pu0
begin -5)H<dAQZ
set @OwnerName = @OldOwner + '.' + rtrim(@Name) q?H|o(
exec sp_changeobjectowner @OwnerName, @NewOwner !-g{[19\
end ]dF
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-- select @name,@NewOwner,@OldOwner 9G9t" {
FETCH NEXT FROM curObject INTO @Name, @Owner ?Lx24*5%
END
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close curObject d.[8c=$
deallocate curObject #?RU;1)Cw
GO 2\R'@L*
10、SQL SERVER中直接循环写入数据 _1!7V3|^
declare @i int xn?a. 3b'
set @i=1 m1j*mtu
while @i<30 QpF;:YX^3
begin vXev$x=w-
insert into test (userid) values(@i) DMs,y{v
set @i=@i+1 b
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end N(O9&L*4fm
小记存储过程中经常用到的本周,本月,本年函数 %9
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Dateadd(wk,datediff(wk,0,getdate()),-1) i9rN9Mq?O
Dateadd(wk,datediff(wk,0,getdate()),6) @g|v;B|{
Dateadd(mm,datediff(mm,0,getdate()),0) u/UrAqw
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) @Rg/~\ K
Dateadd(yy,datediff(yy,0,getdate()),0) Ah1]Y}sy
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) 0}<