Postgres Alter Column Integer to Boolean

I've a field that is INTEGER NOT NULL DEFAULT 0 and I need to change that to bool.

This is what I am using:

ALTER TABLE mytabe
ALTER mycolumn TYPE bool
USING
CASE
WHEN 0 THEN FALSE
ELSE TRUE
END;

But I am getting:

ERROR: argument of CASE/WHEN must be type boolean, not type integer

********** Error **********

ERROR: argument of CASE/WHEN must be type boolean, not type integer
SQL state: 42804


Any idea?


Thanks.

Try this:

ALTER TABLE mytabe ALTER COLUMN mycolumn DROP DEFAULT;
ALTER TABLE mytabe ALTER mycolumn TYPE bool USING CASE WHEN mycolumn=0 THEN FALSE ELSE TRUE END;
ALTER TABLE mytabe ALTER COLUMN mycolumn SET DEFAULT FALSE;


You need to remove the constraint first (as its not a boolean), and secondly your `CASE` statement was syntactically wrong.

Postgres can automatically cast integer to boolean. The key phrase is

using some_col_name::boolean
-- here some_col_name is the column you want to do type change

Above Answer is correct that helped me Just one modification instead of case I used type casting

ALTER TABLE mytabe ALTER COLUMN mycolumn DROP DEFAULT;
ALTER TABLE mytabe ALTER mycolumn TYPE bool USING mycolumn::boolean;
ALTER TABLE mytabe ALTER COLUMN mycolumn SET DEFAULT FALSE;

Also check that you don't have any CHECK constraint on you column like:

`[...] CONSTRAINT blabla CHECK ((field = ANY (ARRAY[0, 1])))`

otherwise you alter command will error with a `cannot convert to boolean type`