Mysql 计算当前日期是本月第几周：一个自定义算法

    Map<String,String> getGroupDate(@Param(value="inputDate") Date inputDate);

   <select id="getGroupDate" parameterType="java.util.Date" resultType="java.util.Map">
        <![CDATA[


    select group_date groupDate from (
    SELECT
    @cdate input_date,
    @last_sat := date_add(date_sub(date_sub(@cdate,interval  day(@cdate)-1 day),interval 1 month), interval 6-date_format(date_sub(date_sub(@cdate,interval  day(@cdate)-1 day),interval 1 month),'%w') day) last_sat,
    @this_sat := date_add(date_sub(@cdate,interval  day(@cdate)-1 day), interval 6-date_format(date_sub(@cdate,interval  day(@cdate)-1 day),'%w') day) this_sat,
    @next_sat := date_add(date_add(date_sub(@cdate,interval  day(@cdate)-1 day),interval 1 month), interval 6-date_format(date_add(date_sub(@cdate,interval  day(@cdate)-1 day),interval 1 month),'%w') day) next_sat,
    @last_point := if(day(@last_sat)-3>0,date_sub(@last_sat,interval 7 day),@last_sat) last_point,
    @this_point := if(day(@this_sat)-3>0,date_sub(@this_sat,interval 7 day),@this_sat) this_point,
    @next_point := if(day(@next_sat)-3>0,date_sub(@next_sat,interval 7 day),@next_sat) next_point ,
    case
    when @cdate >= @last_point and @cdate < @this_point then
    concat(
    'W',
    datediff(@cdate,@last_point) div 7 + 1, '/',
    year(@cdate),'-',
    if(month(@last_sat)>=10,month(@last_sat),concat('0',month(@last_sat)))
    )
    when @cdate >=@this_point and @cdate < @next_point then
    concat(
    'W',
    datediff(@cdate,@this_point) div 7 + 1,'/',
    year(@cdate),'-',
    if(month(@this_sat)>=10,month(@this_sat),concat('0',month(@this_sat))))
    else
    concat(
    'W',
    datediff(@cdate,@next_point) div 7 + 1,'/',
    year(@cdate),'-',if(month(@next_sat)>=10,month(@next_sat),concat('0',month(@next_sat))))
    end
    group_date
    from  (SELECT @cdate := #{inputDate}) as gd
    )；



        ]]>

  </select>