Dynamic SQL replace all columns

sql.SQL

 declare @column varchar(max)
 declare @sql nvarchar(max)
declare @tablename varchar(max)
declare tables cursor for select column_name from INFORMATION_SCHEMA.columns where table_name ='Salesforce_Task_Backup_12102014' and column_name!='ID'
Open tables
Fetch Next FROM tables
 into @column

--set @column='userguid'
--set @value='5000010431119001'
While @@Fetch_Status = 0
Begin
 set @sql=N'update Salesforce_Task_Backup_12102014 set '+ @column+'  = substring('+@column+',1,len('+@column+')-1)'
--set @sql=N'update Salesforce_Task_Backup_12102014 set '+ @column+ ' = right('+@column+',2,len('+@column+')'
-- print @sql
exec sp_executesql @sql

fetch NEXT FROM tables
   Into @column
       End
Close tables
deallocate tables