sql能更新非固定列的数据不

[拖拉板]

sql中是否能实现样更新一个表中非固定列的数据
比如表A ，A1 - A20列 不固定哪一个列的值是xx，现在想把所有的xx更新为yy

[frankl123]

declare @fieldName varchar(100)
		,@sql varchar(200)
declare c cursor for
	select name from syscolumns where id = 
	(select id from sysobjects where name = 'sys_staffdef')
open c
fetch next from c into @fieldName
while @@FETCH_STATUS = 0
begin
	
	set @sql = ' update set sys_staffdef set ' + @fieldName + ' = ''xx'' where ' + @fieldName + ' = ''yy'''
	exec (@sql)
	
fetch next from c into @fieldName
end
close c
deallocate c

[拖拉板]

非常感谢，学习了