练习1:查询90号部门的员工信息
#练习:查询90号部门的员工信息
SELECT * FROM employees
WHERE department_id = 90; #过滤条件
练习2:查询90号部门的员工信息
#练习:查询last_name为'King'的员工信息
SELECT * FROM employees
WHERE last_name = 'King'
练习3:查询员工12个月的工资总和,并起别名为ANNUAL SALARY
SELECT employee_id,last_name,first_name,salary * 12 "ANNUAL SALARY"
FROM employees
练习4:查询employees表中去除重复的job_id后的数据
SELECT DISTINCT job_id FROM employees
练习5:查询employees表中去除重复的job_id后的数据
SELECT last_name,first_name,salary
FROM employees
WHERE salary>12000
练习6: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;
练习7:显示表 departments 的结构,并查询其中的全部数据
DESC departments; #查询表结构(DESCRIBE或DESC)
SELECT * FROM departments; #查询全部数据