PostgreSQLで外部キー制約をON DELETE CASCADEにする方法

SELECT 'ALTER TABLE "'||nspname||'"."'||relname||'" DROP CONSTRAINT "'||conname||'";'
 FROM pg_constraint 
 INNER JOIN pg_class ON conrelid=pg_class.oid 
 INNER JOIN pg_namespace ON pg_namespace.oid=pg_class.relnamespace 
 WHERE contype='f' 
 ORDER BY CASE WHEN contype='f' THEN 0 ELSE 1 END,contype,nspname,relname,conname

SELECT
    'ALTER TABLE "' || 'public' || '".' || conrelid ::regclass || ' ADD CONSTRAINT ' || conname || ' FOREIGN KEY ('
     || a.attname || ') REFERENCES ' || confrelid ::regclass || ' (' || af.attname || ') ON DELETE CASCADE;'
     as al1
    , 'ALTER TABLE "' || 'public' || '".' || conrelid ::regclass || ' ADD CONSTRAINT ' || conname || ' FOREIGN KEY ('
     || a.attname || ') REFERENCES ' || confrelid ::regclass || ' (' || af.attname || ');' as al2 
FROM
    pg_constraint 
    INNER JOIN pg_attribute a 
        ON a.attrelid = pg_constraint.conrelid 
        and a.attnum = ANY (pg_constraint.conkey) 
    INNER JOIN pg_attribute af 
        ON af.attrelid = pg_constraint.confrelid 
        and af.attnum = ANY (pg_constraint.confkey) 
        AND af.attrelid = pg_constraint.confrelid 
WHERE
    contype = 'f';