1 说明：复制表(只复制结构,源表名：a 新表名：b)
sql: select * into b from a where 1<>1
2 说明：拷贝表(拷贝数据,源表名：a 目标表名：b)
sql: insert into b(a, b, c) select d,e,f from b;
select * into b from a
3 说明：显示文章、提交人和最后回复时间
sql: select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b
4 说明：外连接查询(表名1：a 表名2：b)
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
5 说明：日程安排提前五分钟提醒
sql: select * from 日程安排 where datediff(''minute'',f开始时间,getdate())>5
6 说明：两张关联表，删除主表中已经在副表中没有的信息
sql:
delete from info where not exists ( select * from infobz where info.infid=infobz.infid
7 说明：四表联查问题：
sql: 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 .....
8 说明：得到表中最小的未使用的id号
sql:
select (case when exists(select * from handle b where b.handleid = 1) then min(handleid) + 1 else 1 end) as handleid
from handle
where not handleid in (select a.handleid - 1 from handle a)
9 sql 2000 中修改字段的默认值:
declare @name varchar(100)
select @name=b.name from syscolumns a,sysobjects b where a.id=object_id(N'表名')
and b.id=a.cdefault and a.name='字段' and b.name like 'DF%'
exec('Alter table 表名 DROP CONSTRAINT ' + @name )
只需修改表名和字段名即可;
10 判断表T_Inform 是否存在字段InStoreDeptClassID ,如果不存在加入该字段:
if (NOT exists ( select * from dbo.syscolumns where name = 'InStoreDeptClassID' and id in
(select id from dbo.sysobjects where id = object_id(N'[dbo].[T_Inform]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)))
ALTER TABLE dbo.T_Inform ADD InStoreDeptClassID varchar(50) NULL
GO
11 设表T_ReceiveInStore 中有字段ID和InStorePerson,客户要求他们只能看到自己分公司的资料,因此在表中加入一个字段instoreDeptClassID,用于表示分公司的ID;前面客户已经输入相关的资料,因此根据InStorePerson到公司类别表T_DeptClass中找deptClassID (小弟做了张视图V_PersonToDeptClass )更新instoreDeptClassID,如下:
update T_ReceiveInStore set instoreDeptClassID=(select deptClassID from V_PersonToDeptClass where personname = InStorePerson)
12 查看当前用户每个表占用空间的大小：
Select Segment_Name,Sum(bytes)/1024/1024 From User_Extents Group By Segment_Name
13 oracle创建用户
create user JZX identified by JZX345 default tablespace users Temporary TABLESPACE Temp;
grant connect,resource,dba to JZX;
commit;
很多的技巧是我不知道的,小弟还望各位大哥多多帮忙,有好的发表上来我一起加入.....
Oracle:
exp jzx/jzx345@jzx201 file=d:jzx201_0520.dmp full=y
ALTER USER system ACCOUNT UNLOCK;
