File Content: insert_username.example DROP TABLE username_test; CREATE TABLE username_test ( name text, username text not null ); CREATE TRIGGER insert_usernames BEFORE INSERT OR UPDATE ON username_test FOR EACH ROW EXECUTE PROCEDURE insert_username (username); INSERT INTO username_test VALUES ('nothing'); INSERT INTO username_test VALUES ('null', null); INSERT INTO username_test VALUES ('empty string', ''); INSERT INTO username_test VALUES ('space', ' '); INSERT INTO username_test VALUES ('tab', ' '); INSERT INTO username_test VALUES ('name', 'name'); SELECT * FROM username_test; Submit