Re: Compare columns

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Peppe wrote:
Hi guys,
I really need some help.
I have two tables tbl_question with 2 columns question_id , question_name
and
tbl_answers with 3 columns answer_id,answer_name and questionFK.
I want to get values from question_id and compare them with questionFK if
some values are missing in questionFK then I need a insert of missing
values.
values from questionFK have to be always same as question_id

I'm not sure if you can do this all in one step but what you want is an outer join:

select question_id, question_name from tbl_questions q left outer join tbl_answers a on q.question_id=a.questionFK where a.questionFK IS NULL;

Once you know which questions are unanswered you can insert the rows you need.

insert into tbl_answers (questionFK) SELECT question_id from tbl_questions q left outer join tbl_answers a on q.question_id=a.questionFK where a.questionFK IS NULL;

I'd check the results of the first query before running the second one.

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