CONVERT A TABLE COLUMN(CHAR) TO ANOTHER DATA TYPE(INTEGER)

If you want to change character to integer in postgresql use the following



1) Create a function
CREATE OR REPLACE FUNCTION otc_chartoint(chartoconvert character varying)
  RETURNS integer AS
$BODY$
SELECT CASE WHEN trim($1) SIMILAR TO '[0-9]+'
        THEN CAST(trim($1) AS integer)
    ELSE NULL END;

$BODY$
  LANGUAGE 'sql' IMMUTABLE STRICT;



2)Run this query
 ALTER TABLE <Table Name> ALTER COLUMN <Column Name> TYPE integer USING otc_chartoint(<Column Name>);