MySQL练习整理（每日习题）

# 1.查询员工12个月的工资总和，并起别名为ANNUAL SALARY 
#第一种理解方式,只计算了基本工资
SELECT employee_id,last_name,salary * 12 "ANNUAL SALARY"
FROM employees; 
#第二种理解方式，基本工资加上了奖金  用到了IFNULL的语句
SELECT employee_id,last_name,salary * 12 * (1 + IFNULL (commission_pct,0))"ANNUAL SALARY"
FROM employees;

#2.查询employees表中去除重复的job_id以后的数据
SELECT DISTINCT job_id
FROM employees;

# 3.查询工资大于12000的员工姓名和工资 
SELECT last_name,salary
FROM employees
WHERE salary >= 12000;

# 4.查询员工号为176的员工的姓名和部门号
SELECT last_name,department_id
FROM employees
WHERE employee_id = 176;

# 5.显示表 departments 的结构，并查询其中的全部数据
DESC departments;
SELECT * FROM departments;