一、问题描述：
1。在sql server 中，ntext/text/image 字段不允许应用replace函数替换内容；
2。通过convert字段转换，可以把ntext字段转换为varchar（8000），然后用relpace函数替换，不过，此方法，对于字段长度大于8000的ntext字段无效。
二、问题解决
整理通用存储过程，代码如下：
复制代码 代码如下:
create procedure [dbo].[proc_updatentextfield]
@targettable nvarchar(1000), –目标表名
@targetfield nvarchar(1000), –目标字段名
@pkfield nvarchar(1000), –该表主键字段名
@otxt nvarchar(1000), –需要替换的字符串
@ntxt nvarchar(1000) –替换后的字符串
as
begin
declare @sqlstr nvarchar(4000)
set @sqlstr = ‘ declare @txtlen int ‘
set @sqlstr = @sqlstr + ‘ set @txtlen = len(”’ + @otxt + ”’) ‘
set @sqlstr = @sqlstr + ‘ declare @pos int ‘
set @sqlstr = @sqlstr + ‘ set @pos = 0 ‘
set @sqlstr = @sqlstr + ‘declare curs cursor local fast_forward for select ‘
set @sqlstr = @sqlstr + @pkfield + ‘ , textptr(‘ + @targetfield +’) from ‘ + @targettable +’ where ‘ + @targetfield + ‘ like ”%’ + @otxt +’%”’
set @sqlstr = @sqlstr + ‘ declare @ptr binary(16) ‘
set @sqlstr = @sqlstr + ‘ declare @id char(32) ‘
set @sqlstr = @sqlstr + ‘ open curs ‘
set @sqlstr = @sqlstr + ‘ fetch next from curs into @id, @ptr ‘
set @sqlstr = @sqlstr + ‘ while @@fetch_status = 0 ‘
set @sqlstr = @sqlstr + ‘ begin ‘
set @sqlstr = @sqlstr + ‘ select @pos= patindex(”%’ + @otxt + ‘%”,productdesc) from producttemp where productid=@id ‘
set @sqlstr = @sqlstr + ‘ while @pos>0 ‘
set @sqlstr = @sqlstr + ‘ begin ‘
set @sqlstr = @sqlstr + ‘ set @pos=@pos-1 ‘
set @sqlstr = @sqlstr + ‘ updatetext ‘ + @targettable + ‘.’ +@targetfield + ‘ @ptr @pos @txtlen ”’ + @ntxt + ”’ ‘
set @sqlstr = @sqlstr + ‘ select @pos= patindex(”%’ + @otxt + ‘%”,productdesc) from producttemp where productid=@id ‘
set @sqlstr = @sqlstr + ‘ end ‘
set @sqlstr = @sqlstr + ‘ fetch next from curs into @id, @ptr ‘
set @sqlstr = @sqlstr + ‘ end ‘
set @sqlstr = @sqlstr + ‘ close curs ‘
set @sqlstr = @sqlstr + ‘ deallocate curs ‘
execute sp_executesql @sqlstr
end