why_mysql_is_shit.sql

mysql> CREATE TABLE products(
    -> id INT PRIMARY KEY NOT NULL auto_increment,
    -> name VARCHAR(255) NOT NULL,
    -> quantity INT NOT NULL
    -> );
Query OK, 0 rows affected (0.22 sec)

mysql> INSERT INTO products(name) VALUES("First product");
Query OK, 1 row affected, 1 warning (0.02 sec)

mysql> SELECT * FROM products;
+----+---------------+----------+
| id | name          | quantity |
+----+---------------+----------+
|  1 | First product |        0 |
+----+---------------+----------+
1 row in set (0.00 sec)

why_postgresql_is_good.sql

test_sql=# CREATE TABLE products(
test_sql(# id SERIAL PRIMARY KEY,
test_sql(# name VARCHAR(255) NOT NULL,
test_sql(# quantity INT NOT NULL
test_sql(# );
CREATE TABLE

test_sql=# INSERT INTO products(name) VALUES ('First product');
ERROR:  null value in column "quantity" violates not-null constraint
DETAIL:  Failing row contains (1, First product, null).