How to drop constraints in postgres?

Question

I have this query in SQL:

IF EXISTS (SELECT * FROM dbo.sysobjects WHERE id = object_id('[FK_states_list]') AND OBJECTPROPERTY(id, 'IsForeignKey') = 1)
ALTER TABLE [custom_table] DROP CONSTRAINT [FK_states_list] ;

How can I write this query in Postgres?

score 106 · Accepted Answer · 2016-09-15 13:51:38Z

106

It seems you want to drop the constraint, only if it exists.

In Postgres you can use:

ALTER TABLE custom_table 
  DROP CONSTRAINT IF EXISTS fk_states_list;

You can also make sure the table exists:

ALTER TABLE IF EXISTS custom_table 
  DROP CONSTRAINT IF EXISTS fk_states_list;

edited Sep 15, 2016 at 13:51

answered Sep 15, 2016 at 13:37

user330315

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1 Comment

TheRealChx101 Over a year ago

This is why PostgreSQL is the best. You cannot do IF EXISTS in MySQL. What a sad thing.

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