如何在所有日期获得结果？

Question

在此查询中，我只获得WET＆gt; = 6的日期值。这些天我怎么能得到'0'？

SELECT
DATE(DTM) AS 'Dia',
CASE
WHEN (AVG(TMP)<13 OR COUNT(WET)=0) THEN '0'
WHEN ((AVG(TMP)>=13 AND AVG(TMP)<17) AND (COUNT(TMP)/4>=0 AND COUNT(TMP)/4<6)) THEN '0'
WHEN ((AVG(TMP)>=13 AND AVG(TMP)<17) AND (COUNT(TMP)/4>=6 AND COUNT(TMP)/4<15)) THEN '1'
WHEN ((AVG(TMP)>=13 AND AVG(TMP)<17) AND (COUNT(TMP)/4>=15 AND COUNT(TMP)/4<20)) THEN '2'
WHEN ((AVG(TMP)>=13 AND AVG(TMP)<17) AND (COUNT(TMP)/4>=20)) THEN '3'
END
AS 'DSV TOMCAST'
FROM dados_meteo
WHERE WET>=6/* AND POM='[VARIABLE]'*/
GROUP BY DATE(DTM)

Answer 1

正如我现在所理解的那样，当没有WET >= 6的记录时，你想要返回一个默认值。您可以使用此处描述的技术完成此操作：

Oracle: Get a query to always return exactly one row, even when there's no data to be found