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。 E {UhM q7
f8-~&N/_R
B<ZCuVWH:
一、基础 D;z!C
ys
1、说明:创建数据库 9{0%M
CREATE DATABASE database-name u qA!#E
2、说明:删除数据库 zXk^ugFy
drop database dbname / 2MhP=,
3、说明:备份sql server $."Fz
x
--- 创建 备份数据的 device #<G:&
USE master ,{_56j^d,
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat' -`$J& YU
--- 开始 备份 !&5|:96o
BACKUP DATABASE pubs TO testBack 89t"2|9 u
4、说明:创建新表 /Mj|Px%
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..) 8( Q[A
根据已有的表创建新表: 5 BeU/
A:create table tab_new like tab_old (使用旧表创建新表) {\X$vaF
B:create table tab_new as select col1,col2... from tab_old definition only TN<"X :x9
5、说明:删除新表 0^)~p{Zh
drop table tabname n`!6EaD
6、说明:增加一个列 8mt#S
Alter table tabname add column col type %S^:5#9
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。 H9Vn(A8&`
7、说明:添加主键: Alter table tabname add primary key(col) `JyI`@,!
说明:删除主键: Alter table tabname drop primary key(col)
^CD?SP"i
8、说明:创建索引:create [unique] index idxname on tabname(col....) }"[/BT5t
删除索引:drop index idxname I8|"h8\
注:索引是不可更改的,想更改必须删除重新建。 } ?MbU6"
9、说明:创建视图:create view viewname as select statement +BE_t(%p"
删除视图:drop view viewname n4.\}%=z
10、说明:几个简单的基本的sql语句 k%iwt]i%
选择:select * from table1 where 范围 i-.AD4
插入:insert into table1(field1,field2) values(value1,value2) 2b Fr8FUt-
删除:delete from table1 where 范围 v=cX.^L
更新:update table1 set field1=value1 where 范围 ~du U& \
查找:select * from table1 where field1 like '%value1%' ---like的语法很精妙,查资料!
zjSHa'9*
排序:select * from table1 order by field1,field2 [desc] 5mZwg(si
总数:select count as totalcount from table1 g?*D)WU
求和:select sum(field1) as sumvalue from table1 TP/bX&bjCy
平均:select avg(field1) as avgvalue from table1 nRT]oAi
最大:select max(field1) as maxvalue from table1 !_oR/)
最小:select min(field1) as minvalue from table1 uX%$3k
w-C%,1F,/
TaF;PGjVw
QB !%
11、说明:几个高级查询运算词 _C19eW'
T7o7t5*
q
s:TR
A: UNION 运算符 C=2DxdZG
UNION 运算符通过组合其他两个结果表(例如 TABLE1 和 TABLE2)并消去表中任何重复行而派生出一个结果表。当 ALL 随 UNION 一起使用时(即 UNION ALL),不消除重复行。两种情况下,派生表的每一行不是来自 TABLE1 就是来自 TABLE2。 bf.yA:~U
B: EXCEPT 运算符 7 0EH~
EXCEPT 运算符通过包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重复行而派生出一个结果表。当 ALL 随 EXCEPT 一起使用时 (EXCEPT ALL),不消除重复行。 hZWkw{c
C: INTERSECT 运算符 eU.C<Tv:8
INTERSECT 运算符通过只包括 TABLE1 和 TABLE2 中都有的行并消除所有重复行而派生出一个结果表。当 ALL 随 INTERSECT 一起使用时 (INTERSECT ALL),不消除重复行。 2B5Ez,'#x
注:使用运算词的几个查询结果行必须是一致的。 x:h)\%Dg<
12、说明:使用外连接 c2L\m*^o
A、left outer join: [.6bxK
左外连接(左连接):结果集几包括连接表的匹配行,也包括左连接表的所有行。 B
]sVlbt
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c M.bkFuh
B:right outer join: PDLps[a
右外连接(右连接):结果集既包括连接表的匹配连接行,也包括右连接表的所有行。 jv6>7@<G
C:full outer join: 1=e(g#Ajn\
全外连接:不仅包括符号连接表的匹配行,还包括两个连接表中的所有记录。 lXEnm-_
; P$ _:-C
qn'TIE.
二、提升 Sr_hD5!
1、说明:复制表(只复制结构,源表名:a 新表名:b) (Access可用) BB_(!omq[
法一:select * into b from a where 1<>1 OX?E3 <8`
法二:select top 0 * into b from a L[<CEk
2、说明:拷贝表(拷贝数据,源表名:a 目标表名:b) (Access可用) ^ >
?C
insert into b(a, b, c) select d,e,f from b; ^/#8 "
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) oFT1d
insert into b(a, b, c) select d,e,f from b in '具体数据库' where 条件 yo%Nz"
例子:..from b in '"&Server.MapPath(".")&"\data.mdb" &"' where.. [
$"
4、说明:子查询(表名1:a 表名2:b) #K iqV6E
select a,b,c from a where a IN (select d from b ) 或者: select a,b,c from a where a IN (1,2,3) K@Xj)
5、说明:显示文章、提交人和最后回复时间 lkC| g%f
select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b |C5{[ z
6、说明:外连接查询(表名1:a 表名2:b) JY,oXA6O
select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c FlY"OU*
7、说明:在线视图查询(表名1:a ) 2fNNdxdbT
select * from (SELECT a,b,c FROM a) T where t.a > 1; HrMbp
8、说明:between的用法,between限制查询数据范围时包括了边界值,not between不包括 EQX<<x"
select * from table1 where time between time1 and time2 "-j96
KD
select a,b,c, from table1 where a not between 数值1 and 数值2 x(p/9$.#
9、说明:in 的使用方法 m\E=I5*/
select * from table1 where a [not] in ('值1','值2','值4','值6') `cIeqp
10、说明:两张关联表,删除主表中已经在副表中没有的信息 3+q-yP#X
delete from table1 where not exists ( select * from table2 where table1.field1=table2.field1 ) A,(9|#%L
11、说明:四表联查问题: r;E5e]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 ..... V#R; -C
12、说明:日程安排提前五分钟提醒 ZI8@ 6 L\
SQL: select * from 日程安排 where datediff('minute',f开始时间,getdate())>5 /!y;h-
13、说明:一条sql 语句搞定数据库分页 P#
U|
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 lHHx D
14、说明:前10条记录 px(~ZZB"
select top 10 * form table1 where 范围 Lr(JnS
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.) ="PFCxi
select a,b,c from tablename ta where a=(select max(a) from tablename tb where tb.b=ta.b) XqwP<5Z
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 .F[5{XV
(select a from tableA ) except (select a from tableB) except (select a from tableC) d/awQXKe7
17、说明:随机取出10条数据 P0U&+^W"9
select top 10 * from tablename order by newid() 4ElS_u^cP7
18、说明:随机选择记录 C~'.3Q6
select newid() ?^LG>GgV
19、说明:删除重复记录 d`%7Pk
Delete from tablename where id not in (select max(id) from tablename group by col1,col2,...) b!teSf
20、说明:列出数据库里所有的表名 .[1@wW&L
select name from sysobjects where type='U' *P&lAyt6
21、说明:列出表里的所有的 g>`D!n::n
select name from syscolumns where id=object_id('TableName') B__e*d:)!m
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。 .9Dncsnf,`
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 N9M",(WTt}
显示结果: Vup|*d2r0E
type vender pcs -KfMKN~
电脑 A 1 z4zPR?%:
电脑 A 1 :bL^S1et
光盘 B 2 x}=Q)|)]
光盘 A 2 WM4,\$
手机 B 3 B}K<L\S
手机 C 3 J,s:CBCGL
23、说明:初始化表table1 FMzG6nrdBN
TRUNCATE TABLE table1 6&L;Sw#Dg
24、说明:选择从10到15的记录 @\>7
wt_'
select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc 2 zG;91^
6E(..fo:"
` .]oH1\
nT(AO-Ue^
三、技巧 I1s$\NZ~]
1、1=1,1=2的使用,在SQL语句组合时用的较多 lhf5[Rp
"where 1=1" 是表示选择全部 "where 1=2"全部不选, #\O'*mz
如: QIJ/'72
if @strWhere !='' i [Wxu M
begin =}Q|#C
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where ' + @strWhere D 5:'2i
end sM%l:Fv
else
8-cuaa
begin 2 gca*
set @strSQL = 'select count(*) as Total from [' + @tblName + ']' :"b :uQ
end Vn\jUEC
我们可以直接写成 \'|t>|zhp
set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere n-,mC/4
2、收缩数据库 &qIdT;^=I
--重建索引 $ub0$S/Hu
DBCC REINDEX VN$7r
DBCC INDEXDEFRAG a=v H:D
--收缩数据和日志 WGyPyG#Fl
DBCC SHRINKDB Dd-a*6|x
DBCC SHRINKFILE rj?c
3、压缩数据库 4$U^)\06W
dbcc shrinkdatabase(dbname) E]S:F3
4、转移数据库给新用户以已存在用户权限 K$r)^K=s
exec sp_change_users_login 'update_one','newname','oldname' .YP&E1lNi
go Y]5MM:mI
5、检查备份集 `)MKCw$e
RESTORE VERIFYONLY from disk='E:\dvbbs.bak' q!~DCv df
6、修复数据库 [$:L|V!{
ALTER DATABASE [dvbbs] SET SINGLE_USER #q-fRZ:P
GO /s+S\
djk
DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK
bf2r8
GO PzhC *" i}
ALTER DATABASE [dvbbs] SET MULTI_USER w@n}DCFt
GO C}DIm&))
7、日志清除 1TF S2R n
SET NOCOUNT ON 7@m+y
DECLARE @LogicalFileName sysname, }OTJ{eG
@MaxMinutes INT, z2!4w +2
@NewSize INT BN&}g}N
USE tablename -- 要操作的数据库名 c6y>]8_
SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 ,dVJAV7v
@MaxMinutes = 10, -- Limit on time allowed to wrap log. /FC(d5I
@NewSize = 1 -- 你想设定的日志文件的大小(M) 8HHR
-- Setup / initialize vo2GFo
DECLARE @OriginalSize int ={;+0Wjb8
SELECT @OriginalSize = size m}S}fH(
FROM sysfiles YD{N)v
WHERE name = @LogicalFileName ?{5}3abB`
SELECT 'Original Size of ' + db_name() + ' LOG is ' + X|QokAR{$>
CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + L{&=SR.
CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' Vo%Z|
FROM sysfiles {z;4t&5
WHERE name = @LogicalFileName " SP6o
CREATE TABLE DummyTrans Xs'qwL~{`
(DummyColumn char (8000) not null) >$)~B4
DECLARE @Counter INT, wfcR[
@StartTime DATETIME, 1?.NJ<)F
@TruncLog VARCHAR(255) {vZAOz7#
SELECT @StartTime = GETDATE(), w ykaf
@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY' 6UL9+9[C
DBCC SHRINKFILE (@LogicalFileName, @NewSize) z<0/#OP'
EXEC (@TruncLog) 2"%f:?xV{
-- Wrap the log if necessary.
/<%L&
WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired SZ7; }
r8
AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) ]mgpd}Y
AND (@OriginalSize * 8 /1024) > @NewSize ASr@5uFR
BEGIN -- Outer loop. .b^!f<j
SELECT @Counter = 0 >.G#\w
WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) 7u5H o`
BEGIN -- update 3f~znO
INSERT DummyTrans VALUES ('Fill Log') U3 UA
DELETE DummyTrans '#.D`9YI<
SELECT @Counter = @Counter + 1 tDfHO1pS
END WN#2<XjG
EXEC (@TruncLog) ya,-Lt
END h^''ue"
SELECT 'Final Size of ' + db_name() + ' LOG is ' + UN:qE oS
CONVERT(VARCHAR(30),size) + ' 8K pages or ' + '*
/$66|
CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' D,(:))DmR
FROM sysfiles ,ei=w,O
WHERE name = @LogicalFileName [nrD4
DROP TABLE DummyTrans QXl~a%lB
SET NOCOUNT OFF U\-.u3/
8、说明:更改某个表 z^WY5~?
exec sp_changeobjectowner 'tablename','dbo' >&F:/
9、存储更改全部表 jpoNTl'
CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch rls{~ZRl
@OldOwner as NVARCHAR(128), x~{W(;`!
@NewOwner as NVARCHAR(128) N%1nii
AS vg_PMy\
DECLARE @Name as NVARCHAR(128) x\VP
X
DECLARE @Owner as NVARCHAR(128) bka%W@Y%
DECLARE @OwnerName as NVARCHAR(128) `0!%jz=
DECLARE curObject CURSOR FOR 4T
v=sP
select 'Name' = name, rq}xuSFI
'Owner' = user_name(uid) gkKNOus
from sysobjects BW`;QF<
where user_name(uid)=@OldOwner `VDvxl@1
order by name B7.&yXWgn
OPEN curObject +Z"[2Dm
FETCH NEXT FROM curObject INTO @Name, @Owner `~41>mM%
WHILE(@@FETCH_STATUS=0) &!M6{O=~
BEGIN
a3a:H
if @Owner=@OldOwner q(1hY"S"}b
begin crSqbL
set @OwnerName = @OldOwner + '.' + rtrim(@Name) Y4X`(\A
exec sp_changeobjectowner @OwnerName, @NewOwner @e$EwCV,
end fE3%$M[V7
-- select @name,@NewOwner,@OldOwner }1lZW"{e[
FETCH NEXT FROM curObject INTO @Name, @Owner )V*`(dn'zm
END ?U1Nm~'UZ
close curObject T1x67 b
u
deallocate curObject NX:\iJD)1U
GO JLjs`oqh
10、SQL SERVER中直接循环写入数据 }_@p`>|)rB
declare @i int t}OzF cyqN
set @i=1 1F3Q^3+
while @i<30 2k&Voa
begin ]v]:8>N
insert into test (userid) values(@i) W ,v0~
set @i=@i+1 *O)i)["
end iWW
>]3Q
小记存储过程中经常用到的本周,本月,本年函数 /WK1( B:
Dateadd(wk,datediff(wk,0,getdate()),-1) }Gx@1)??
Dateadd(wk,datediff(wk,0,getdate()),6) kVG+Wr7l0F
Dateadd(mm,datediff(mm,0,getdate()),0) ]&P 4QT)f
Dateadd(ms,-3,dateadd(mm,datediff(m,0,getdate())+1,0)) *Ue#Sade
Dateadd(yy,datediff(yy,0,getdate()),0) [UB*39D7
Dateadd(ms,-3,DATEADD(yy, DATEDIFF(yy,0,getdate())+1, 0)) 0W+RVp=TL1
上面的SQL代码只是一个时间段 [8oX[oP
Dateadd(wk,datediff(wk,0,getdate()),-1) wL6G&6]</W
Dateadd(wk,datediff(wk,0,getdate()),6) S?OCy4dk:
就是表示本周时间段. Z/4bxO=m
下面的SQL的条件部分,就是查询时间段在本周范围内的: %5@>
nC?`[
Where Time BETWEEN Dateadd(wk,datediff(wk,0,getdate()),-1) AND Dateadd(wk,datediff(wk,0,getdate()),6) :1@jl2,
而在存储过程中 kr!>rqN5
select @begintime = Dateadd(wk,datediff(wk,0,getdate()),-1) PpF`0w=1%l
select @endtime = Dateadd(wk,datediff(wk,0,getdate()),6) |)*!&\Ch