對錶中每個季度的資料進行統計並實現自動補零，首先先查詢出表中每個季度的資料

SELECT QUARTER(applicationdate) as mon, COUNT(*) as con FROM qm_technical_zero GROUP BY QUARTER(applicationdate)

從表qm_technical_zero中按季度查詢日期applicationdate的資料，但是隻能出現前三季度的資料，第四季度為零所以不顯示。

結果如下所示

然後在建立一個表

SELECT  1 as click_date UNION ALL
SELECT  2 as click_date UNION ALL
SELECT  3 as click_date UNION ALL
SELECT  4 as click_date
 

結果如下圖所示

然後對兩個表進行聯合查詢就可以實現補零操作。
 

SELECT click_date as q,IFNULL(b.con,0) as c FROM(SELECT  1 as click_date UNION ALL
SELECT  2 as click_date UNION ALL
SELECT  3 as click_date UNION ALL
SELECT  4 as click_date) a LEFT JOIN(
SELECT QUARTER(applicationdate) as mon, COUNT(*) as con FROM qm_technical_zero GROUP BY QUARTER(applicationdate))
b ON click_date=b.mon
 

進行聯合查詢後結果如下所示：