I have a table called type: type ------- type_id integer tvalue smallint ... .. .. tvalue was a second key on this table which now turns out to be unnecessary. Before I can remove it I need to change the columns which reference it. I wanted to do this with alter table alter column using But the using clause I am using does not work. I think I may just be misunderstanding how this is done, but I could only find a few examples. Here is an example of what I have tried: alter table service.service alter column environment_tvalue type integer using select type.type.type_id where tvalue = environment_tvalue and typeset_id = 1; Does the expression in the using clause have to be a function? Any advice would be appreciated. Thanks, Craig
