SQL 基础命令 入门

查询

SELETE * FROM students 这条命令查询出 students 表中 所有的数据

SELETE name, age, gender FROM students 这条命令查询出 表中 name, age, gender 字段

SELETE name, age, gender FROM students WHILE age >= 20 查询符合条件age >= 20

设置别名

SELETE name _name, age _age, gender _gender FROM students s 把表名设置别名为 s, 字段名name, age, gender 设置别名为 _name, _age, _gender

多表查询

SELETE * FROM students，classes 查询students , classes两张表的所有数据

连接查询

SELETE * FROM students INNER JOIN classes ON class_id = students_id 查询students , classes两张表class_id = students_id的数据并集

SELETE * FROM students LEFT OUTER JOIN classes ON class_id = students_id 查询students , classes两张表class_id = students_id的数据左并集

SELETE * FROM students RIGHT OUTER JOIN classes ON class_id = students_id 查询students , classes两张表class_id = students_id的数据右并集

SELETE * FROM students FULL OUTER JOIN classes ON class_id = students_id 查询students , classes两张表class_id = students_id的数据并集

插入

INSERT INTO students (class_id, name, gender, score) VALUES (2, '大牛', 'M', 80); 插入数据

const obj = {
        class_id : 2,
        name: '大牛',
        gender: 'M',
        score: 80
    }

删除

DELETE FROM students WHERE id=1 删除表中 id=1的所有数据

更新

UPDATE students SET name='大牛', score=66 WHERE id=1 更新表中 id=1 所有数据 name='大牛', score=66

学习SQL记录总结