表连接查询
多表查询的分类:
两个表数据
CREATE TABLE dept(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(20)
);
CREATE TABLE emp(
id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(10),
gender CHAR(1),
salary DOUBLE,
join_date DATE,
dept_id INT,
FOREIGN KEY (dept_id) REFERENCES dept(id)
)
# 插入数据
insert into d