Disable constraints for child tables

SELECT
    'ALTER TABLE '||TABLE_NAME||' DISABLE CONSTRAINTS '||CONSTRAINT_NAME||';'
FROM
    user_constraints
WHERE
    r_constraint_name =
    (SELECT constraint_name FROM user_constraints WHERE
        lower(table_name) = 'parent_table' AND constraint_type = 'P')
    AND constraint_type = 'R'
;