CREATE TABLE customer (

customer_id mediumint(8) unsigned NOT NULL auto_increment,

gender enum('female','male','') NOT NULL,

firstname varchar(50) NOT NULL,

lastname varchar(50) NOT NULL,

PRIMARY KEY (customer_id)

);

INSERT INTO customer VALUES (1, 'female', 'Dagmar', 'Bösel');

INSERT INTO customer VALUES (2, 'male', 'Dietmar', 'Maier');

INSERT INTO customer VALUES (3, 'female', 'Sabine', 'Kanter');

CREATE TABLE sales1 (

sale_id mediumint(8) unsigned NOT NULL auto_increment,

customer_id mediumint(8) unsigned NOT NULL,

sale_amount decimal(10,2) NOT NULL,

sale_date datetime NOT NULL,

PRIMARY KEY (sale_id)

);

INSERT INTO sales1 VALUES (1, 3, 14.40, '2007-04-02 11:37:06');

INSERT INTO sales1 VALUES (2, 1, 28.30, '2007-05-14 11:37:18');

INSERT INTO sales1 VALUES (3, 2, 34.40, '2007-05-06 11:38:14');

INSERT INTO sales1 VALUES (4, 2, 25.60, '2007-05-07 11:38:39');

CREATE TABLE sales2 (

sale_id mediumint(8) unsigned NOT NULL auto_increment,

customer_id mediumint(8) unsigned NOT NULL,

sale_amount decimal(10,2) NOT NULL,

sale_date datetime NOT NULL,

PRIMARY KEY (sale_id)

);

INSERT INTO sales2 VALUES (1, 2, 68.20, '2007-04-06 11:37:06');

INSERT INTO sales2 VALUES (2, 3, 21.30, '2007-04-12 11:37:18');

INSERT INTO sales2 VALUES (3, 3, 54.40, '2007-05-06 11:38:14');

INSERT INTO sales2 VALUES (4, 1, 35.70, '2007-05-07 11:38:39');