过滤数据

• • WHERE
  • 比较运算符
  • • 基本操作符
    • 其他比较运算符
    • • between..and
      • in
      • like
  • 逻辑运算符
  • 算数运算符

WHERE

SELECT employee_id, last_name, job_id, department_id 
FROM employees 
WHERE department_id = 90 ;

比较运算符

基本操作符

SELECT last_name, salary 
FROM employees 
WHERE salary <= 3000;

其他比较运算符

between…and

SELECT last_name, salary 
FROM employees 
WHERE salary BETWEEN 2500 AND 3500;
# WHERE salary>=2500 AND salary<=3500;

in

SELECT employee_id, last_name, salary, manager_id 
FROM employees 
WHERE manager_id IN (100, 101, 201); # 无顺序
# WHERE manager_id=100 OR manager_id=101 OR manager_id=201;

like

模糊查询

逻辑运算符

算数运算符