1.     sql trim()函数去掉两头空格

sql语法中没有直接去除两头空格的函数，但有ltrim()去除左空格rtrim()去除右空格。
合起来用就是sql的trim()函数，即select ltrim(rtrim(UsrName))

 2.    
sql触发器常用语法

这是一个自动采购的触发器，主要需要注意的触发条件，以及临时表的作用。

创建触发器 CREATE TRIGGER tr_update_Stock 

删除触发器 DROP
 TRIGGER tr_update_Stock 

禁用：
ALTER TABLE trig_example DISABLE TRIGGER trig1
GO
恢复：
ALTER TABLE trig_example ENABLE TRIGGER trig1
GO

—————————————————————

–禁用某个表上的所有触发器
ALTER TABLE 你的表 DISABLE TRIGGER all

–启用某个表上的所有触发器
ALTER TABLE 你的表 enable TRIGGER all

–禁用所有表上的所有触发器
exec sp_msforeachtable ‘ALTER TABLE ? DISABLE TRIGGER all’

–启用所有表上的所有触发器
exec sp_msforeachtable ‘ALTER TABLE ? enable TRIGGER all’

 3. 在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢：

1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断 
select * from people 
where peopleId in (select peopleId from people group by peopleId having
count(peopleId) > 1) 

2、删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录 
delete from people 
where   peopleName in (select peopleName    from
people group by peopleName      having
count(peopleName) > 1) 
and   peopleId not in (select min(peopleId) from people group by
peopleName     having count(peopleName)>1) 

3、查找表中多余的重复记录（多个字段） 
select * from vitae a 
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq
having count(*) > 1) 

4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录 
delete from vitae a 
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by
peopleId,seq having count(*) > 1) 
and rowid not in (select min(rowid) from vitae group by peopleId,seq having
count(*)>1) 

5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录 
select * from vitae a 
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by
peopleId,seq having count(*) > 1) 
and rowid not in (select min(rowid) from vitae group by peopleId,seq having
count(*)>1)   

6.消除一个字段的左边的第一位：

update tableName set
[Title]=Right([Title],(len([Title])-1)) where Title like ‘村%’

7.消除一个字段的右边的第一位：

update tableName set
[Title]=left([Title],(len([Title])-1)) where Title like ‘%村’

8.假删除表中多余的重复记录（多个字段），不包含rowid最小的记录 
update vitae set ispass=-1
where peopleId in (select peopleId from vitae group by peopleId

4.  
 批量更新：

UPDATE TABLE_1

   
SET COL_1=TT2.RESULT_COL_1,COL_2=TT2.RESULT_COL_2

FROM TABLE1 AS TT1

INNER JOIN (SELECT
RESULT_COL_1,RESULT_COL_2 FROM TABLE_2) AS TT2

ON TT2.RELATION_COL=TT1.RELATION_COL

5.  
全角，半角字符控制

从输出可以看到

1.半角字符是从33开始到126结束

2.与半角字符对应的全角字符是从65281开始到65374结束

3.其中半角的空格是32.对应的全角空格是12288

4.半角和全角的关系很明显,除空格外的字符偏移量是65248(65281-33 = 65248)