sql中生成查询的模糊匹配字符串

网络整理 - 08-25

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_Sql]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_Sql]
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[序数表]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [序数表]
GO

--为了效率,所以要一个辅助表配合
select top 1000 id=identity(int,1,1) into 序数表
from syscolumns a,syscolumns b
alter table 序数表 add constraint pk_id_序数表 primary key(id)
go

/*--根据指定字符串生成查询的模糊匹配字符串

条件连接的关键字为 and,or
可以任意指定括号
生成的条件表达式为 like 模糊匹配

--邹建 2004.08(引用请保留此信息)--*/

/*--调用示例

--调用示例
select A=dbo.f_Sql('(Web or HTML or Internet) and (Programmer or Developer)','content')
select B=dbo.f_Sql('Web or HTML or Internet','content')
select C=dbo.f_Sql('(Web and HTML)','content')
select D=dbo.f_Sql('Web','content')
--*/
--示例函数
create function f_Sql(
@str Nvarchar(1000), --要检索的字符串
@fdname sysname --在那个字段中检索
)returns Nvarchar(4000)
as
begin
declare @r Nvarchar(4000)
set @r=''
select @r=@r+case
  when substring(@str,id,charindex(' ',@str+' ',id)-id) in('or','and')
   then ' '+substring(@str,id,charindex(' ',@str+' ',id)-id)+' '
  when substring(@str,id,1)='('
   then '(['+@fdname+'] like ''%'
    +substring(@str,id+1,charindex(' ',@str+' ',id)-id-1)
    +'%'''
  when substring(@str,charindex(' ',@str+' ',id)-1,1)=')'
   then '['+@fdname+'] like ''%'
    +substring(@str,id,charindex(' ',@str+' ',id)-id-1)
    +'%'')'
  else '['+@fdname+'] like ''%'
   +substring(@str,id,charindex(' ',@str+' ',id)-id)
   +'%'''
  end
from 序数表
where id<=len(@str)
  and charindex(' ',' '+@str,id)-id=0
return(@r)
end
go