MySQL-表操作

#语法：
create table 表名(
字段名1 类型[(宽度) 约束条件],
字段名2 类型[(宽度) 约束条件],
字段名3 类型[(宽度) 约束条件]
);

#注意：
1. 在同一张表中，字段名是不能相同
2. 宽度和约束条件可选
3. 字段名和类型是必须的

mysql> create database tt character set utf8;
Query OK, 1 row affected (0.00 sec)

mysql> use tt;
Database changed
mysql> create table t1(
    -> id int,
    -> name varchar(50),
    -> sex enum(‘male‘,‘female‘),
    -> age int(3)
    -> );
Query OK, 0 rows affected (0.10 sec)

mysql> show tables;
+--------------+
| Tables_in_tt |
+--------------+
| t1           |
+--------------+
1 row in set (0.00 sec)

mysql> desc t1;
+-------+-----------------------+------+-----+---------+-------+
| Field | Type                  | Null | Key | Default | Extra |
+-------+-----------------------+------+-----+---------+-------+
| id    | int(11)               | YES  |     | NULL    |       |
| name  | varchar(50)           | YES  |     | NULL    |       |
| sex   | enum(‘male‘,‘female‘) | YES  |     | NULL    |       |
| age   | int(3)                | YES  |     | NULL    |       |
+-------+-----------------------+------+-----+---------+-------+
4 rows in set (0.01 sec)

mysql> select id,name,sex,age from t1;
Empty set (0.00 sec)

mysql> select * from t1;
Empty set (0.00 sec)
mysql> select id,name,sex from t1;
Empty set (0.00 sec)