流程控制语句IF和CASE

# IF类似于JAVA中的三目运算符  表达式1成立 则返回表达式2 反之 返回表达式3

SELECT IF(10>5,'大','小');

SELECT employees.last_name,employees.commission_pct,IF(employees.commission_pct IS NULL,'呵呵没奖金','嘻嘻有奖金') FROM employees;

# CASE

SELECT employees.salary 原始工资,employees.department_id,

CASE employees.department_id

WHEN 30 THEN employees.salary*1.1

WHEN 40 THEN employees.salary*1.2

WHEN 50 THEN employees.salary*1.3

ELSE employees.salary

END AS 新工资

FROM employees;