Mysql多表联合查询

create table user(
user_id int primary key auto_increment,
user_name varchar(50),
dept_id tinyint,
age tinyint
);

create table dept(
dept_id int,
dept_name varchar(50)
);

mysql> use test;
Database changed
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| student        |
| user           |
| v_a            |
+----------------+
3 rows in set (0.00 sec)

mysql> create database emp;
Query OK, 1 row affected (0.13 sec)

mysql> use emp;
Database changed
mysql> create table user(
->  user_id int primary key auto_increment,
->  user_name varchar(50),
->  dept_id tinyint,
->  age tinyint
-> );
Query OK, 0 rows affected (0.20 sec)

mysql> create table dept(
->     dept_id int,
->     dept_name varchar(50)
-> );
Query OK, 0 rows affected (0.24 sec)

mysql> show tables;
+---------------+
| Tables_in_emp |
+---------------+
| dept          |
| user          |
+---------------+
2 rows in set (0.00 sec)