多表查询之连接查询

版权声明：17602128911 https://blog.csdn.net/bus_lupe/article/details/88409363

外键约束

主表：classcharger

CREATE TABLE ClassCharger(
  id TINYINT PRIMARY  KEY auto_increment,
  name VARCHAR(20),
  age INT,
  is_marriged TINYINT
);

INSERT INTO ClassCharger (name, age, is_married) VALUES
  ("冰冰", 52, 0),
  ("丹丹", 34, 0),
  ("歪歪", 32, 0),
  ("珊珊", 28, 0),
  ("小雨", 61, 0);

子表：student2

CREATE TABLE Student2(
  id INT PRIMARY KEY auto_increment,
  name VARCHAR (20),
  charger_id TINYINT,
  FOREIGN KEY(charger_id) REFERENCES classcharger(id)
)

INSERT INTO Student2(name, charger_id) values ("alvin1", "2"),
  ("alvin2", "4"),
  ("alvin3", "1"),
  ("alvin4", "3"),
  ("alvin5", "1"),
  ("alvin6", "3"),
  ("alvin7", "2");