1. 查询出部门编号为30的所有员工
select * from yg where deptno = 30;
2. 所有销售员的姓名、编号和部门编号。
select ename,empno,deptno from yg where job = "销售员";
3. 找出奖金高于工资的员工。
select * from yg where comm > sal;
4. 找出奖金高于工资60%的员工。
select * from yg where comm > 0.6*sal;
5. 找出部门编号为10中所有经理，和部门编号为20中所有销售员的详细资料。
select * from yg where (deptno = 10 and job = "经理")or(deptno = 20 and job = "销售员");
6.找出部门编号为10中所有经理，部门编号为20中所有销售员，还有即不是经理又不是销售员但其工资大或等于20000的所有员工详细资料。
select * from yg where (deptno = 10 and job = "经理")or(deptno = 20 and job = "销售员")or(job not in("经理","销售员") and sal >= 20000);
7.无奖金或奖金低于1000的员工。
select * from yg where comm <= 1000 or comm is null;
8. 查询名字由三个字组成的员工。
select * from yg where ename like "___";
9.查询2000年入职的员工。
select * from yg where hiredate like "2000%";
select * from yg where hiredate >= "2000-01-01" and hiredate <= "2000-12-31";
10. 查询所有员工详细信息，用编号升序排序
select * from yg order by empno asc;
11. 查询所有员工详细信息，用工资降序排序，如果工资相同使用入职日期升序排序
select * from yg order by sal desc,hiredate asc;
12.查询姓周的两个名字的员工。
select * from yg where ename like "周_";
查询所有姓张的员工。
select * from yg where ename like "张%";