正常方法是
left join：
select wd.wd, count(t.id)from (select 1 as wd union all select 2 union all select 3 union all select 4 uion all select 5 union all select 6 union all select 7 ) wd left join test t on wd.wd = weekday(t.date)group by wd.wdorder by wd.wd;
