mariadb_testing.sql

MariaDB [(none)]> create database testing;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> use testing;
Database changed
MariaDB [testing]> 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 (0.01 sec)

MariaDB [testing]> INSERT INTO products(name) VALUES("First product");
Query OK, 1 row affected, 1 warning (0.00 sec)

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

MariaDB [testing]> ALTER TABLE products ADD COLUMN price DECIMAL(6,2) NOT NULL;
Query OK, 1 row affected (0.03 sec)
Records: 1  Duplicates: 0  Warnings: 0

MariaDB [testing]> SELECT * FROM products;
+----+---------------+----------+-------+
| id | name          | quantity | price |
+----+---------------+----------+-------+
|  1 | First product |        0 |  0.00 |
+----+---------------+----------+-------+
1 row in set (0.00 sec)

MariaDB [testing]> UPDATE products SET price=100 WHERE id=1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

MariaDB [testing]> SELECT * FROM products;
+----+---------------+----------+--------+
| id | name          | quantity | price  |
+----+---------------+----------+--------+
|  1 | First product |        0 | 100.00 |
+----+---------------+----------+--------+
1 row in set (0.00 sec)

MariaDB [testing]> ALTER TABLE products MODIFY price DECIMAL(2,2) NOT NULL;
Query OK, 1 row affected, 1 warning (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 1

MariaDB [testing]> SELECT * FROM products;
+----+---------------+----------+-------+
| id | name          | quantity | price |
+----+---------------+----------+-------+
|  1 | First product |        0 |  0.99 |
+----+---------------+----------+-------+
1 row in set (0.00 sec)