Mysql: Adding a complex constraint on the table

Asked Aug 07 '17 at 14:37

Active Aug 07 '17 at 14:44

Viewed 31 times

I have table say - T with columns as <a,b,c>. <A,B> is the primary key of the table. Now I need to put a constraint on relationship A->C such that for an a there can be multiple rows with c as 0, but only one row as 1.

I understand that we can put simple constraint in mysql such as - don't add column with specific values(CHECK constraint in MySQL is not working). but I am not able to find a way to put such a complex constraint. Do I need to denormalize the table? or do I need to put a check in the code for the sanity check?.

edited Aug 07 '17 at 14:44

asked Aug 07 '17 at 14:37

Mangat Rai Modi

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Use a trigger to simulate CHECK constraint – Raymond Nijland Aug 07 '17 at 14:44
can I have check constraint on the data in table rather than value I am inserting? – Mangat Rai Modi Aug 07 '17 at 14:45
Can you please provide the CREATE/ALTER-statements which you have tried so far? – Myonara Aug 08 '17 at 18:06

Mysql: Adding a complex constraint on the table

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