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。 44!bwXz8
ZW2U9
G*ecM`Bl
一、基础 =T[kGg8`
1、说明:创建数据库 &TKB8vx=#
CREATE DATABASE database-name %#=
1?1s
2、说明:删除数据库 #fQStO
drop database dbname 8kk$:8
3、说明:备份sql server J:t1W=lJ3
--- 创建 备份数据的 device 1|2X0Xm{
USE master LcQ \d*
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' lE4.O
--- 开始 备份 Y#KgaZ7N
BACKUP DATABASE pubs TO testBack i),W1<A1
4、说明:创建新表 "/K44(^
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) zT.qNtU%
根据已有的表创建新表: U`xjau+
A:create table tab_new like tab_old (使用旧表创建新表) >XBLm`a
B:create table tab_new as select col1,col2... from tab_old definition only $cjidBi`):
5、说明:删除新表 zI&oZH^vn
drop table tabname U\+o$mU^
6、说明:增加一个列 9mr99tA
Alter table tabname add column col type }=NjFK_6
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。 lV3\5AEW
7、说明:添加主键: Alter table tabname add primary key(col) XJ.vj+XXb
说明:删除主键: Alter table tabname drop primary key(col) <Dl7|M
8、说明:创建索引:create [unique] index idxname on tabname(col....) nT:ZSJWM
删除索引:drop index idxname O0e6I&u:
注:索引是不可更改的,想更改必须删除重新建。 SwLul4V
9、说明:创建视图:create view viewname as select statement h&&ufF]D
删除视图:drop view viewname $Die~rPU
10、说明:几个简单的基本的sql语句 O.}{s;
选择:select * from table1 where 范围 ;'*"(F=D6
插入:insert into table1(field1,field2) values(value1,value2) @Kp2l<P
删除:delete from table1 where 范围 OX I.>9
更新:update table1 set field1=value1 where 范围 K%.\@l2Cp
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! awGI|d
排序:select * from table1 order by field1,field2 [desc] (z\@T`6`
总数:select count as totalcount from table1 %+qD-{&
求和:select sum(field1) as sumvalue from table1 "d9"Md0k
平均:select avg(field1) as avgvalue from table1 LJ9^:U
最大:select max(field1) as maxvalue from table1 }5\F <b^@Y
最小:select min(field1) as minvalue from table1 (z#qkKL{^
y^?7de}
Z%k)'%_
p1q"[)WVn^
11、说明:几个高级查询运算词 Bi9 S1p
,..&j+m
a?_N8|k[
A: UNION 运算符 }O-|b#Q
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 `J#(ffo-
B: EXCEPT 运算符 DR;rK[f
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 NZ7g}+GTG
C: INTERSECT 运算符 O$+0 .
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。 abp]qvCV
注:使用运算词的几个查询结果行必须是一致的。 CtfI&rb[
12、说明:使用外连接 #3leMZ6
A、left outer join: Z+x,Awq
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。 |\Nu+w
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 !ffdeWHR
B:right outer join: {%*,KB>b
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。 R_`i=>Z-
C:full outer join: :2vk
vLM
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。 vvwNJyU-
)%I2#Q"Nt-
}KcvNK (
二、提升 \9N1:
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) Z_Qs^e$
法一:select * into b from a where 1<>1 FWNWOU
法二:select top 0 * into b from a A\X?Aq-^'
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) :XqqhG
insert into b(a, b, c) select d,e,f from b; PRg^E4
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) &'Pwz
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 2r4owB?
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. h\k@7wgu
4、说明:子查询(表名1:a 表名2:b) c 2t<WRG
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) @9Rgg9r
5、说明:显示文章、提交人和最后回复时间 R7pdwKD
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b `fYICp
6、说明:外连接查询(表名1:a 表名2:b) -{n2^vvF
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c ge
%ytrst
7、说明:在线视图查询(表名1:a ) /}t>o*
x
select * from (SELECT a,b,c FROM a) T where t.a > 1; p~Di\AQ/
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 j51Wod<[
select * from table1 where time between time1 and time2 >+Z BQ]~
select a,b,c, from table1 where a not between 数值1 and 数值2 FxeDjAP
9、说明:in 的使用方法 e)"]H*
select * from table1 where a [not] in ('值1','值2','值4','值6') ?NkweT(
10、说明:两张关联表,删除主表中已经在副表中没有的信息 ,T&=*q
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) OeLM*Zi
11、说明:四表联查问题: d^p af
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 ..... %&w 8E[
12、说明:日程安排提前五分钟提醒 [$:M/5y9
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 Ws$<B
b
13、说明:一条sql 语句搞定数据库分页 7L)edR[
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 Oh)s"f\N
14、说明:前10条记录 (xxNQ]
l-(
select top 10 * form table1 where 范围 R9bsl.e
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.) dnRbt{`jP
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) HGM ?
?=
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 sxc^n
aK0
(select a from tableA ) except (select a from tableB) except (select a from tableC) ;r'y/Y'?
17、说明:随机取出10条数据 b|jdYJbol&
select top 10 * from tablename order by newid() qRi;[`
18、说明:随机选择记录 jd ]$U_U(
select newid() J'{69<`Dl
19、说明:删除重复记录 |[qq
$
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) Z1Y/2MVSb
20、说明:列出数据库里所有的表名 !'scOWWn
select name from sysobjects where type='U' ?'SHt9b3|
21、说明:列出表里的所有的 NX.%Rj*
select name from syscolumns where id=object_id('TableName') [Ume^
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。 tjLp;%6e
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 \A
"_|Yg
显示结果: " ,k(*
type vender pcs V;}kgWc1
电脑 A 1 !A_<(M<
电脑 A 1 B"KDr_,,
光盘 B 2 dRC
RB
光盘 A 2 /L |$*
Xj
手机 B 3 _%M+!Ltz
手机 C 3 $r> $
u
23、说明:初始化表table1 -QPM$
TRUNCATE TABLE table1 "$P|!k45(
24、说明:选择从10到15的记录 gbf2ty
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc d6RO2^
n`v;S>aT
zt,Tda4Y
%*:X
FB
三、技巧 tFj[>_d7
1、1=1,1=2的使用,在SQL语句组合时用的较多 (p6$Vgdt
"where 1=1" 是表示选择全部 "where 1=2"全部不选, [k<"@[8)
如: V/N:Of:\R
if @strWhere !='' lSW6\jX
begin F"I{_yleq'
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere -O&u;kh4g
end V%|CCrR
else <d*;d3gm
begin &ZyZmB
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' 8nV#\J9
end x&^>|'H
我们可以直接写成 *,x-}%X
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere d;:H#F+ (
2、收缩数据库 7tZvz `\
--重建索引 1VXyn\
DBCC REINDEX +,8j]<wpo
DBCC INDEXDEFRAG b\
P6,s'(
--收缩数据和日志 FR57F(31
DBCC SHRINKDB @$:T]N3m
DBCC SHRINKFILE Nj5V" c
3、压缩数据库 X6h@K</c^:
dbcc shrinkdatabase(dbname) s*XE
4、转移数据库给新用户以已存在用户权限 UYw_k\
exec sp_change_users_login 'update_one','newname','oldname' *HC[LM
go 3P}^Wu
5、检查备份集 N*mm[F2+F
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' O4c[,Uq8~
6、修复数据库 85{2TXQ^%=
ALTER DATABASE [dvbbs] SET SINGLE_USER Nd;)V
GO \+9~\eeXb
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK Ire+r
"am
GO xbTvv>'U
ALTER DATABASE [dvbbs] SET MULTI_USER B me_#
GO s8O.yL
7、日志清除 OCX>LK!K
SET NOCOUNT ON J`I^F:y*
DECLARE @LogicalFileName sysname, !PySYY
@MaxMinutes INT, LvM;ZfAEv
@NewSize INT 0aWy!d
USE tablename -- 要操作的数据库名 3)ZdT{MY
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 = n>aJ(=Pd
@MaxMinutes = 10, -- Limit on time allowed to wrap log. {.r
jp`39
@NewSize = 1 -- 你想设定的日志文件的大小(M) [c`u
-- Setup / initialize ?=^~(x?S
DECLARE @OriginalSize int %@q/OVnM
SELECT @OriginalSize = size M94zlW<
FROM sysfiles 3QZ~t#,7ij
WHERE name = @LogicalFileName O>vbAIu
SELECT 'Original Size of ' + db_name() + ' LOG is ' + tMy<MO)Ei
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + U07G&?/
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' tJ qd
FROM sysfiles AiDV4lHr
WHERE name = @LogicalFileName =cP7"\
CREATE TABLE DummyTrans BH;7CK=7R
(DummyColumn char (8000) not null) ~ZxFL$<'3
DECLARE @Counter INT, )8,) &F
@StartTime DATETIME, Sd9%tO9mf
@TruncLog VARCHAR(255) (>)f#t[9J
SELECT @StartTime = GETDATE(), 7^hwRZJ{
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' Y%GIKtP
DBCC SHRINKFILE (@LogicalFileName, @NewSize) fR^aFT
EXEC (@TruncLog) :nLhg$wMs
-- Wrap the log if necessary. Yw!(]8PYdU
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired >}I BPC
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) Ho^rYz
AND (@OriginalSize * 8 /1024) > @NewSize 2a,l;o$2&
BEGIN -- Outer loop. n){F
FM
SELECT @Counter = 0 bMCy=5
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) ^Gt9.
BEGIN -- update n !oxwA!
INSERT DummyTrans VALUES ('Fill Log') Cg]Iz<<bE
DELETE DummyTrans
MYk%p'
SELECT @Counter = @Counter + 1 Nn:>c<[
END `A0trC3
EXEC (@TruncLog) vR*TW
END sM _m
SELECT 'Final Size of ' + db_name() + ' LOG is ' + CS\ E]f
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + #q-7#pp
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' A}h`%b
FROM sysfiles =X24C'!Mpe
WHERE name = @LogicalFileName ajJ+Jn\
DROP TABLE DummyTrans 5h!ZoB)n
SET NOCOUNT OFF WF&?OHf2
8、说明:更改某个表 n7$21*,
exec sp_changeobjectowner 'tablename','dbo' No(p:Snbo
9、存储更改全部表 q33Z.3R
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch $Y3mO~
@OldOwner as NVARCHAR(128), #ouE,<
@NewOwner as NVARCHAR(128) Pkq?tm$#
AS ,x]xtg?
DECLARE @Name as NVARCHAR(128) wMx#dP4W8
DECLARE @Owner as NVARCHAR(128) oBpoZ @[Z
DECLARE @OwnerName as NVARCHAR(128) I `I+7~t
DECLARE curObject CURSOR FOR $TK<~3`
select 'Name' = name, ? 3'O
'Owner' = user_name(uid) W&'[Xj
from sysobjects Up*.z\|'y
where user_name(uid)=@OldOwner MmL)CT
order by name m.':5
OPEN curObject uB*Y}"Fn
FETCH NEXT FROM curObject INTO @Name, @Owner ),%(A~\
WHILE(@@FETCH_STATUS=0) -0G/a&ss
BEGIN $KAOJc4<
if @Owner=@OldOwner 0^G5 zQlj
begin xkPH_+4i8
set @OwnerName = @OldOwner + '.' + rtrim(@Name) K:_5#!*^98
exec sp_changeobjectowner @OwnerName, @NewOwner #y2IHO-
end <5fb,@YN
-- select @name,@NewOwner,@OldOwner MzP
q(`W
FETCH NEXT FROM curObject INTO @Name, @Owner )_-EeH
END KhFw%Z0s<
close curObject gOSFvH8FU
deallocate curObject 2*5]6B-(
GO *?<ygzX
10、SQL SERVER中直接循环写入数据 qHtonJc
declare @i int x<lY&KQ0
set @i=1 XqxmvN
while @i<30 ,+mH1#-3
begin []#>r
k~
insert into test (userid) values(@i) =TcT` ](o
set @i=@i+1 y<0RgG1qp
end NJqjW
小记存储过程中经常用到的本周,本月,本年函数 !\(j[d#
Dateadd(wk,datediff(wk,0,getdate()),-1) %7vjYvo>
Dateadd(wk,datediff(wk,0,getdate()),6) *l9Wj$vja
Dateadd(mm,datediff(mm,0,getdate()),0) L3s1a -K
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) o)}M$}4
Dateadd(yy,datediff(yy,0,getdate()),0) J.;{`U=:
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) xJemc3]2
上面的SQL代码只是一个时间段 O3];1ud
Dateadd(wk,datediff(wk,0,getdate()),-1) 1Bl;.8he.)
Dateadd(wk,datediff(wk,0,getdate()),6) u}~j NV
就是表示本周时间段. k&M9Hn2
下面的SQL的条件部分,就是查询时间段在本周范围内的: _=*ph0nu
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) K>_~zW nc
而在存储过程中 |tVWmm^m
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) c1>:|D7w
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) eCfy'US;@3