现统计每个人员的工资等级,请问SQL语句怎么写啊?谢谢

人员表:   
人名               工龄           薪金类别   
a1                   4               月薪 
a2                   5               日薪   
a3                   6               日薪 工资等级表:   序号                               条件                                               工资等级     
d1                       工龄   <   4                                        001   
d2                       工龄>   =4       and       工龄   <5                 002   
d3                       工龄>   =5       and       工龄   <6                 003   
现统计每个人员的工资等级,请问SQL语句怎么写啊?谢谢