select max(cast(date_add+ ' ' + left(cast(time_add as varchar(8)),2) + ':' + substring (cast(time_add as varchar(8)), 3, 2)
+ ':' + substring (cast(time_add as varchar(8)), 5, 2) + ':' + right (cast(time_add as varchar(8)), 2)) as datetime) from int_table
im getting an missing keyword error...