mysql> SHOW TABLES;
+-----------------+
| Tables_in_maizi |
+-----------------+
| cms_cate |
| cms_news |
| course |
| test1 |
| test10 |
| test11 |
| test2 |
| test3 |
| test4 |
| test5 |
| test6 |
| test7 |
| test8 |
| test9 |
| user |
+-----------------+
15 rows in set (0.00 sec)
mysql> CREATE TABLE IF NOT EXISTS user1(
-> id INT PRIMARY KEY,
-> username VARCHAR(20)
-> );
Query OK, 0 rows affected (0.30 sec)
mysql> DESC user1;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(11) | NO | PRI | NULL | |
| username | varchar(20) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
mysql> SHOW CREATE TABLE user1;
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------+
| user1 | CREATE TABLE `user1` (
`id` int(11) NOT NULL,
`username` varchar(20) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.02 sec)
mysql> INSERT user1 VALUES(1,'king');
Query OK, 1 row affected (0.07 sec)
mysql> INSERT user1 VALUES(13,'QUEEN');
Query OK, 1 row affected (0.03 sec)
mysql> SELECT * FROM user1;
+----+----------+
| id | username |
+----+----------+
| 1 | king |
| 13 | QUEEN |
+----+----------+
2 rows in set (0.00 sec)
mysql> INSERT user1 VALUES(13,'QUEEN');
ERROR 1062 (23000): Duplicate entry '13' for key 'PRIMARY'
mysql> SELECT * FROM user1 WHERE id=1;
+----+----------+
| id | username |
+----+----------+
| 1 | king |
+----+----------+
1 row in set (0.00 sec)
mysql> CREATE TABLE IF NOT EXISTS user2(
-> id INT,
-> username VARCHAR(20),
-> card CHAR(18),
-> PRIMARY KEY(id,card)
-> );
Query OK, 0 rows affected (0.23 sec)
mysql> DESC user2;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(11) | NO | PRI | 0 | |
| username | varchar(20) | YES | | NULL | |
| card | char(18) | NO | PRI | | |
+----------+-------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql> INSERT user2 VALUES(1,'king','111');
Query OK, 1 row affected (0.05 sec)
mysql> SELECT * FROM user2;
+----+----------+------+
| id | username | card |
+----+----------+------+
| 1 | king | 111 |
+----+----------+------+
1 row in set (0.00 sec)
mysql> INSERT user2 VALUES(1,'queen','112');
Query OK, 1 row affected (0.06 sec)
mysql> SELECT * FROM user2;
+----+----------+------+
| id | username | card |
+----+----------+------+
| 1 | king | 111 |
| 1 | queen | 112 |
+----+----------+------+
2 rows in set (0.00 sec)
mysql> INSERT user2 VALUES(1,'queen','112');
ERROR 1062 (23000): Duplicate entry '1-112' for key 'PRIMARY'
mysql> SHOW CREATE TABLE user2;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| user2 | CREATE TABLE `user2` (
`id` int(11) NOT NULL DEFAULT '0',
`username` varchar(20) DEFAULT NULL,
`card` char(18) NOT NULL DEFAULT '',
PRIMARY KEY (`id`,`card`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> CREATE TABLE IF NOT EXISTS user3(
-> id INT KEY,
-> username VARCHAR(20)
-> );
Query OK, 0 rows affected (0.39 sec)
mysql> DESC user3;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(11) | NO | PRI | NULL | |
| username | varchar(20) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
mysql> CREATE TABLE IF NOT EXISTS user4(
-> id INT,
-> username VARCHAR(20) KEY
-> );
Query OK, 0 rows affected (0.44 sec)
mysql> DESC user4;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| username | varchar(20) | NO | PRI | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
mysql> CREATE TABLE IF NOT EXISTS user5(
-> id SMALLINT KEY AUTO_INCREMENT,
-> username VARCHAR(20)
-> );
Query OK, 0 rows affected (0.34 sec)
mysql> DESC user5;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | smallint(6) | NO | PRI | NULL | auto_increment |
| username | varchar(20) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
2 rows in set (0.11 sec)
mysql> INSERT user5 VALUES(1,'KING');
Query OK, 1 row affected (0.06 sec)
mysql> INSERT user5(username) VALUES('queen');
Query OK, 1 row affected (0.07 sec)
mysql> SELECT * FROM user5;
+----+----------+
| id | username |
+----+----------+
| 1 | KING |
| 2 | queen |
+----+----------+
2 rows in set (0.00 sec)
mysql> INSERT user5 VALUES(111,'KING1');
Query OK, 1 row affected (0.04 sec)
mysql> SELECT * FROM user5;
+-----+----------+
| id | username |
+-----+----------+
| 1 | KING |
| 2 | queen |
| 111 | KING1 |
+-----+----------+
3 rows in set (0.00 sec)
mysql> INSERT user5(username) VALUES('queen1');
Query OK, 1 row affected (0.07 sec)
mysql> SELECT * FROM user5;
+-----+----------+
| id | username |
+-----+----------+
| 1 | KING |
| 2 | queen |
| 111 | KING1 |
| 112 | queen1 |
+-----+----------+
4 rows in set (0.00 sec)
mysql> SHOW CREATE TABLE user5;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------
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