浅析SQLServer中的Scanf与Printf(代码字符串)

1、xp_sscanf，用它可以分解格式相对固定的字符串，这对于厌倦使用一堆substring和charindex的朋友来说不错。比如前几天的一个帖子中提出的如何分解ip地址，相对简练且通用的代码应该是下面这样

复制代码代码如下:

if (object_id ('f_getip' ) is not null )

drop function f_getip 

go 

create function dbo . f_getip (@ ip varchar (100 ))

returns @ t table (a int , b int , c int , d int )

as 

begin 

 set @ ip = replace (@ ip , '.' , ' ' )

 declare 

 @ s1 varchar (3 ) , @ s2 varchar (3 ), 

 @ s3 varchar (3 ) , @ s4 varchar (3 )

 exec xp_sscanf @ ip , '%s %s %s %s' , @ s1 output , @ s2 output , @ s3 output , @ s4 output 

 insert into @ t select @ s1 , @ s2 , @ s3 , @ s4 

 return 

end 

go 

select * from dbo . f_getip ('192.168.0.1' )

go 

/* 

a b c d 

----------- ----------- ----------- ----------- 

192 168 0 1 

*/

2、xp_sprintf，用它可以拼接出一个字符串而不用担心过多的加号很引号难以控制，比如一个动态执行sql语句的存储过程

复制代码代码如下:

if (object_id ('p_select' ) is not null )

drop proc p_select 

go 

create proc p_select (@ tb varchar (100 ), @ cols varchar (100 ), @ wherecol varchar (100 ), @ value varchar (100 ))

as 

begin 

 declare @ s varchar (8000 )

 exec xp_sprintf @ s output , 'select %s from %s where %s=''%s''' , @ cols , @ tb , @ wherecol , @ value 

 exec (@ s)

end 

go 

exec p_select 'sysobjects' , 'id,xtype,crdate' , 'name' , 'p_select' 

/* 

id xtype crdate 

----------- ----- ----------------------- 

898102240 P 2009-08-18 03:01:51.153 

*/