1-基本的SELECT语句

#SELECT语句的练习

# 1.查询员工12个月的工资总和，并起别名为ANNUAL SALARY
#理解1：计算12月的基本工资
SELECT employee_id,last_name,salary * 12 "ANNUAL SALARY"
FROM employees;

#理解2：计算12月的基本工资和奖金
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 
DESCRIBE departments;

SELECT * FROM departments;