mysql周数转时间_mysql通过指定周数（IOS周）获取日期

创建：

DELIMITER //

CREATE FUNCTION GetDateByWeek(in_yearweek VARCHAR(10) , in_dayofweek int )

RETURNS DATE

BEGIN

/**

*in_yearweek : '201649'

*in_dayofweek : 1-7 对应周一到周日

*/

declare i_year  VARCHAR(4);

declare i_week  VARCHAR(2);

set i_year = left( in_yearweek ,4);

set i_week = right( in_yearweek ,2);

set in_dayofweek = ifnull(in_dayofweek,1);

select ADDDATE( if( WEEK( MAKEDATE(i_year, 1) , 3)=1,  MAKEDATE(i_year, 1) , ADDDATE( MAKEDATE(i_year, 1),7) ) , (i_week-1)*7 + in_dayofweek-1 -WEEKDAY( MAKEDATE(i_year, 1) )   ) into @result  ;

RETURN @result ;

END //

调用方式 ：

select getDateByWeek('201601',1)