mySQL如何将NULL显示为0-Java 学习之路

在没有数据时，尝试让我的代码显示0而不是NULL：

SELECT e.EntryName AS Name, e.EntryDate AS Date,

(SELECT COALESCE(COUNT(l.crashNumber), 0)
FROM Crash l
WHERE l.crashName = e.EntryName 
AND l.crashDate = e.EntryDate
GROUP BY l.crashNumber
ORDER BY COUNT(l.crashNumber) DESC
LIMIT 1)

FROM 
(SELECT e.EntryName, e.EntryDate
FROM Entry e
GROUP BY e.EntryName, e.EntryDate)

e;

正如你所看到我尝试使用COALESCE，我尝试过使用ISNULL . 我的想法是并非所有种族都有崩溃所以它们的输出显示为NULL，但我希望当它为NULL时它应该显示为0 .

1 回答

使用：

SELECT e.raceEntryRaceName AS raceName, e.raceEntryRaceDate AS raceDate,

Coalesce( ( SELECT COUNT(l.pitstopRaceNumber)
           FROM PitStops l
           WHERE l.pitstopRaceName = e.raceEntryRaceName 
             AND l.pitstopRaceDate = e.raceEntryRaceDate
           GROUP BY l.pitstopRaceNumber
           ORDER BY COUNT(l.pitstopRaceNumber) DESC
           LIMIT 1), 0) AS mostPitstops

FROM .....

回复于 2024-04-29T06:17:07+08:00

mySQL如何将NULL显示为0

1 回答

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