注意自动增长ID必须为键或组合键
mysql> CREATE TABLE pet (
id MEDIUMINT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
sex CHAR(1),
birth DATE,
PRIMARY KEY (id)
);CREATE TABLE animals (
grp ENUM('fish','mammal','bird') NOT NULL,
id MEDIUMINT NOT NULL AUTO_INCREMENT,
name CHAR(30) NOT NULL,
PRIMARY KEY (grp,id)
);
mysql> CREATE TABLE pet (
id MEDIUMINT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
sex CHAR(1),
birth DATE,
PRIMARY KEY (id)
);CREATE TABLE animals (
grp ENUM('fish','mammal','bird') NOT NULL,
id MEDIUMINT NOT NULL AUTO_INCREMENT,
name CHAR(30) NOT NULL,
PRIMARY KEY (grp,id)
);
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