如下兩條常用sql，統(tǒng)計分類數(shù)據(jù)，你能說出區(qū)別嗎？
一、常用sql一：select
r.cid,
r.depart_id,
r.employ_id,
r.create_by,
count(DISTINCT r.form_type) as dailyReportNum
FROM
report r
where
1=1
GROUP BY
r.employ_id
二、常用sql二：
select
r.cid,
r.depart_id,
r.employ_id,
r.create_by,
sum(case WHEN df.form_type=1 then 1 else 0 end ) as dailyReportNum
FROM
report r
where
1=1
GROUP BY
r.employ_id