*FROM employees WHERE email LIKE‘%a%‘OR department_id>90;;
SELECT*FROM employees WHERE email LIKE‘%a%‘UNIONSELECT*FROM employees WHERE department_id>90;
#案例：查询中国用户中男性的信息以及外国用户中年男性的用户信息
SELECT id,cname FROM t_ca WHERE csex=‘男‘UNIONALLSELECT t_id,tname FROM t_ua WHERE tGender=‘male‘;
