Để lại trong mysql

Mệnh đề

CREATE TABLE Teachers [name VARCHAR[30], age INT];

-- Primary key:
CREATE TABLE Teachers [id INT PRIMARY KEY, name VARCHAR[30], age INT]; # primary key: id, không thể lặp lại
CREATE TABLE Students [id INT, name VARCHAR[30], age INT, PRIMARY KEY [code, name, age]]; # primary key là tổ hợp
CREATE TABLE Subjects [id INT PRIMARY KEY NOT NULL AUTO_INCREMENT, name VARCHAR[30]]; # primary key tăng tự động, bắt đầu từ 1, 2, 3...

-- Restrictions:
CREATE TABLE Teachers [id INT PRIMARY KEY NOT NULL, name VARCHAR[30] NOT NULL, age INT NOT NULL]; # NOT NULL: giá trị cột này không thể rỗng
CREATE TABLE Teachers [id INT PRIMARY KEY, name VARCHAR[30], age INT, CHECK [age>18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age18 and age