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。 ')Q
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一、基础 3F?7oMNIh
1、说明:创建数据库 0BwxPD#6bv
CREATE DATABASE database-name p4F%FS:`
2、说明:删除数据库 Y\,aJL$
drop database dbname ["O_Phb|
3、说明:备份sql server ZveNe~D7C
--- 创建 备份数据的 device oE.Ckz~*d
USE master eMV{rFmT
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' |oWl9j]Z
--- 开始 备份 e#U@n
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BACKUP DATABASE pubs TO testBack ;AG&QdTMh
4、说明:创建新表 tj ?%{L
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) r|63T%q!
根据已有的表创建新表: "ejsz&n
A:create table tab_new like tab_old (使用旧表创建新表) )3 I~6ar
B:create table tab_new as select col1,col2... from tab_old definition only ?8w5tfN6t
5、说明:删除新表 `h|Y0x
drop table tabname cP",szcY
6、说明:增加一个列 /Rf,Rjs
Alter table tabname add column col type (@ 1>G
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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。 XU`ly3!
7、说明:添加主键: Alter table tabname add primary key(col) &^UT
说明:删除主键: Alter table tabname drop primary key(col) PNo9.-@G
8、说明:创建索引:create [unique] index idxname on tabname(col....) ew \WV"
删除索引:drop index idxname 4Q!|fn0Sv
注:索引是不可更改的,想更改必须删除重新建。 "38L ,PW0Z
9、说明:创建视图:create view viewname as select statement g~ii^[W
删除视图:drop view viewname d,b]#fj
10、说明:几个简单的基本的sql语句 i zYC0T9
选择:select * from table1 where 范围 ken.#>w
插入:insert into table1(field1,field2) values(value1,value2) y|0!sNg
删除:delete from table1 where 范围 <vE|QxpR
更新:update table1 set field1=value1 where 范围 yH(3 m#
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料! zs(P2$
排序:select * from table1 order by field1,field2 [desc] o}&{Y2!x
总数:select count as totalcount from table1 xHCdtloi?I
求和:select sum(field1) as sumvalue from table1 B"sB0NuT/$
平均:select avg(field1) as avgvalue from table1 Pl. y9g~
最大:select max(field1) as maxvalue from table1 gg/ts]$
最小:select min(field1) as minvalue from table1 <PFF\NE9
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11、说明:几个高级查询运算词 xk
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A: UNION 运算符 (q0vql
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。 \11+~
B: EXCEPT 运算符 M&jlUr&l
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。 {!j)j6(NY
C: INTERSECT 运算符 L PS,\+
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。
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注:使用运算词的几个查询结果行必须是一致的。 v}J0j
12、说明:使用外连接 it-]-=mqb
A、left outer join: F [Lg,}
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。 !>"fDz<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 C;5`G
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B:right outer join: -%0pYB
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。 HOx+umjxW
C:full outer join: Q 5hOVD%
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。 .p]rS
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二、提升 V%{WH}
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) ')}itS8
法一:select * into b from a where 1<>1 {+ Ibi{
法二:select top 0 * into b from a 0~EGrEt
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) E]v]fy"
insert into b(a, b, c) select d,e,f from b; /N({"G'
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) !g`I*ZE+e
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 w=CzPNRHH!
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. p>O/H1US;
4、说明:子查询(表名1:a 表名2:b) o%f:BJS
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) n|pdYe8\
5、说明:显示文章、提交人和最后回复时间 *T#^|<.XG
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b oY5`r)C7
6、说明:外连接查询(表名1:a 表名2:b) $bD`B'5
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c z`YC3_d
7、说明:在线视图查询(表名1:a ) 5*f54g"'
select * from (SELECT a,b,c FROM a) T where t.a > 1; mlCBstt{
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 f`KO#Wc
select * from table1 where time between time1 and time2 }OhSCH'o6
select a,b,c, from table1 where a not between 数值1 and 数值2 o<J6KTLv
9、说明:in 的使用方法 _-sFJi8B
select * from table1 where a [not] in ('值1','值2','值4','值6') !-N!Bt8;
10、说明:两张关联表,删除主表中已经在副表中没有的信息 qe'ssX;
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) )7]yzc
11、说明:四表联查问题: FrUqfTi+W
select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... /\_n5XI1
12、说明:日程安排提前五分钟提醒 +I-BqA9
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 kh{3s:RQfC
13、说明:一条sql 语句搞定数据库分页 :<s`)
select top 10 b.* from (select top 20 主键字段,排序字段 from 表名 order by 排序字段 desc) a,表名 b where b.主键字段 = a.主键字段 order by a.排序字段 ok [_Z;
14、说明:前10条记录 yf;TIh%)=
select top 10 * form table1 where 范围 ]v0Z[l>yf
15、说明:选择在每一组b值相同的数据中对应的a最大的记录的所有信息(类似这样的用法可以用于论坛每月排行榜,每月热销产品分析,按科目成绩排名,等等.) _g
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select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) [Y$TVwFwX
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 S*>T%#F6Uo
(select a from tableA ) except (select a from tableB) except (select a from tableC) NM^uP+uS
17、说明:随机取出10条数据 wx[m-\
select top 10 * from tablename order by newid() gq;>DY]
18、说明:随机选择记录 2NJ\`1HZ\
select newid() Mo<q(_ZeRP
19、说明:删除重复记录
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Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) *Wvk~
20、说明:列出数据库里所有的表名 Bu&9J(J1
select name from sysobjects where type='U' _si 5z
21、说明:列出表里的所有的 @tPr\F
select name from syscolumns where id=object_id('TableName') K3<A<&W_-
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。 ;BqCjS%`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 n((A:b
显示结果: zfE8=d8U
type vender pcs >MKj~Ud
电脑 A 1 k0O5c[j
电脑 A 1 %LzARTX
光盘 B 2 '.;{"G.@'
光盘 A 2 1og+(m`BL
手机 B 3 Cc*R3vHM6
手机 C 3 \'<P~I&p
23、说明:初始化表table1 y 3o3 G
TRUNCATE TABLE table1 }#u #m.
24、说明:选择从10到15的记录 rjiHP;-t1
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc yci} #,nb
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三、技巧 <ShA_+Nd
1、1=1,1=2的使用,在SQL语句组合时用的较多 |0oaEd^*}
"where 1=1" 是表示选择全部 "where 1=2"全部不选, $i6z)]rjg
如: G'p322Bu
if @strWhere !='' ~@Q]@8Tv\
begin xpO;V}M|
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere ;@Fb>lBhX
end czU"
else V2`Ud[
begin uDXV@;6<
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' AoOA.t6RVo
end d@1^U9sf
我们可以直接写成 H<n"[u^@E
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere fqY'Uq$=
2、收缩数据库 oSmETk\
--重建索引 '8\9@wzv
DBCC REINDEX D*[Jrq,
DBCC INDEXDEFRAG [`qdpzUp&
--收缩数据和日志 ~Gz9pBv1
DBCC SHRINKDB e3W~6P
DBCC SHRINKFILE &Jb\}c}
3、压缩数据库 dr}PjwW%
dbcc shrinkdatabase(dbname) =EMB~i
4、转移数据库给新用户以已存在用户权限 f+hHc8g
exec sp_change_users_login 'update_one','newname','oldname' );VuZsmi
go knYp"<qj
5、检查备份集 'sH_^{V2
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' 6
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6、修复数据库 c`p'5qz
ALTER DATABASE [dvbbs] SET SINGLE_USER <$zhNu~
GO 7L6L{~8
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DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK A"&<$5Q
GO CxjB9#
ALTER DATABASE [dvbbs] SET MULTI_USER Xpn\TD<_I
GO [2Zy~`*y{
7、日志清除 0QW=2rs
SET NOCOUNT ON M /v@C*c
DECLARE @LogicalFileName sysname, !rr,(!Ip?O
@MaxMinutes INT, d?J&mLQ6
@NewSize INT ;>jEeIlT
USE tablename -- 要操作的数据库名 9$z$yGjl
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 Vc;[ 0iB
@MaxMinutes = 10, -- Limit on time allowed to wrap log. Tn1V+)
@NewSize = 1 -- 你想设定的日志文件的大小(M) ?#xm6oe#aH
-- Setup / initialize &e:+;7
DECLARE @OriginalSize int ^}p##7t[
SELECT @OriginalSize = size [8IO0lul+
FROM sysfiles wB[f%mHs
WHERE name = @LogicalFileName c+e?xXCEAz
SELECT 'Original Size of ' + db_name() + ' LOG is ' + W"_<SYVJ
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + [bP^RY:
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' pKy4***I3
FROM sysfiles &=jPt%7#M
WHERE name = @LogicalFileName 6Q [
CREATE TABLE DummyTrans } v:YSG
(DummyColumn char (8000) not null) Z s=A<[
DECLARE @Counter INT, NT.#U?9c
@StartTime DATETIME, e
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@TruncLog VARCHAR(255) iaEQF]*cC
SELECT @StartTime = GETDATE(), 7]zZdqG&p`
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' A2:}bb~H
DBCC SHRINKFILE (@LogicalFileName, @NewSize) g,EDE6`8
EXEC (@TruncLog) O_a^|ln&
-- Wrap the log if necessary. {FI*oO1A~
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired [UZr|F
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) rf%lhBv
AND (@OriginalSize * 8 /1024) > @NewSize ]&]DFY~n
BEGIN -- Outer loop. C'|9nK$%
SELECT @Counter = 0 -Q@f),
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) C&H'?0Y@
BEGIN -- update Fy Ih\
INSERT DummyTrans VALUES ('Fill Log') J'|=J
DELETE DummyTrans q0VAkVHw4
SELECT @Counter = @Counter + 1 s$hO/INr
END G/Sp/I<d
EXEC (@TruncLog) n]'
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END XyE$0i~t
SELECT 'Final Size of ' + db_name() + ' LOG is ' + k Alxm{
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + }rfikm
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' (vZ-0Ep}
FROM sysfiles |*NZ^6`@
WHERE name = @LogicalFileName Ld}?da Pj
DROP TABLE DummyTrans O%\cRn8m
SET NOCOUNT OFF 77O$^fG2
8、说明:更改某个表 [m0X kvd
exec sp_changeobjectowner 'tablename','dbo' /"?DOsJ.
9、存储更改全部表 W<prY
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch 8(\}\4G_
@OldOwner as NVARCHAR(128), cZ:jht
@NewOwner as NVARCHAR(128) (b f
IS
AS +:;ddV
DECLARE @Name as NVARCHAR(128) bp:`m>4<
DECLARE @Owner as NVARCHAR(128) K$h\<_V
DECLARE @OwnerName as NVARCHAR(128) y'!OA+ob
DECLARE curObject CURSOR FOR H)D|lt5xy
select 'Name' = name, %T]^,y$n
'Owner' = user_name(uid) K9k!P8Rd
from sysobjects Q*>)W{H&)
where user_name(uid)=@OldOwner n>y,{"J{
order by name 37zBX~
OPEN curObject :,JaOn'
FETCH NEXT FROM curObject INTO @Name, @Owner &/WM:]^?0)
WHILE(@@FETCH_STATUS=0) 5N|LT8P}Z
BEGIN ]E<Z5G1HD
if @Owner=@OldOwner T\}U{9ELL
begin O68-G
set @OwnerName = @OldOwner + '.' + rtrim(@Name) w!20
exec sp_changeobjectowner @OwnerName, @NewOwner 49QsT5b)
end F*PhV|XU
-- select @name,@NewOwner,@OldOwner *{w0=J[15
FETCH NEXT FROM curObject INTO @Name, @Owner M<w.q|P
END K/
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close curObject W7!gD
deallocate curObject '37
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GO 34u[#O{2
10、SQL SERVER中直接循环写入数据 cr!W5+r
declare @i int V)<>W_g
set @i=1 XY'8oU`]{
while @i<30 R<&Euph
begin +ausm!~6
insert into test (userid) values(@i) '2r
set @i=@i+1 <x^$Fu
end Z?'CS|ud
小记存储过程中经常用到的本周,本月,本年函数 H:~p5t
Dateadd(wk,datediff(wk,0,getdate()),-1) 9u(pn`e 3
Dateadd(wk,datediff(wk,0,getdate()),6) G)?*BH
Dateadd(mm,datediff(mm,0,getdate()),0) J.1c,@
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) R
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Dateadd(yy,datediff(yy,0,getdate()),0) %`&n ;K.c
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) .pUB.l$)
上面的SQL代码只是一个时间段 Jj
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Dateadd(wk,datediff(wk,0,getdate()),-1) hUlRtt
Dateadd(wk,datediff(wk,0,getdate()),6) Zt3sU_
就是表示本周时间段. _C/|<Ot:
下面的SQL的条件部分,就是查询时间段在本周范围内的: M?h{'$T
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) G7 UUx+ X
而在存储过程中 ['}|#3*w
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) ML12&E>
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) |KYl'"5\