mysql函數(shù)拼接查詢concat函數(shù)的使用方法

//查詢表managefee_managefee的年year 和 month ,用concat函數(shù)拼成year-month。例如將2017和1 拼成2017-01。.
select CONCAT(a.year,'-',if(a.month=9,CONCAT('0',a.month),a.month))as date,a.* from managefee_managefee as a;

//查詢managefee_managefee中時間段為2017-01到2017-07的數(shù)據(jù)
select * from
(
select CONCAT(a.year,'-',if(a.month=9,CONCAT('0',a.month),a.month))as date,a.* from managefee_managefee as a
) b
where b.date between '2017-01' and '2017-07';