函数中的使用:
BEGIN
declare result tinyint;
set result=0;
if period=0 then
if date=periodData then
set result=1;
end if;
elseif period=1 then
set result=1;
elseif period=2 then
if WEEKDAY(date)+1=periodData then
set result=1;
end if;
elseif period=3 then
if DAYOFMONTH(date)=periodData then
set result=1;
end if;
end if;
RETURN result;
END