来自SQL - CASE语句的意外结果返回的值不是声明的值

Question

谁能帮我解释一下为什么下面更改后的行返回0而不是请求的11或12？我使用的是MySQL，否则这个查询就会正确运行...我正在尝试捕捉上述字段中0和null之间的差异。

    SELECT SUM(CASE WHEN pr.heatEventID=1 THEN pr.points+1 ELSE '-' END) AS `100m`
, SUM(CASE WHEN pr.heatEventID=25 THEN pr.points+1 ELSE '-' END) AS `200m`
, SUM(CASE WHEN pr.heatEventID=37 THEN pr.points+1 ELSE '-' END) AS `400m`
, SUM(CASE WHEN pr.heatEventID=49 THEN pr.points+1 ELSE '-' END) AS `800m`
, SUM(CASE WHEN pr.heatEventID=61 THEN pr.points+1 ELSE '-' END) AS `1500m`
, SUM(CASE WHEN pr.heatEventID=67 THEN (CASE WHEN pr.points IS NULL THEN 11 ELSE 12 END) ELSE '' END) AS `3000m`
, SUM(CASE WHEN pr.heatEventID=69 THEN pr.points+1 ELSE '-' END) AS `Javelin`
, SUM(CASE WHEN pr.heatEventID=81 THEN pr.points+1 ELSE '-' END) AS `Shot Put`
, SUM(CASE WHEN pr.heatEventID=93 THEN pr.points+1 ELSE '-' END) AS `Discus`
, SUM(CASE WHEN pr.heatEventID=105 THEN pr.points+1 ELSE '-' END) AS `High Jump`
, SUM(CASE WHEN pr.heatEventID=117 THEN pr.points+1 ELSE '-' END) AS `Long Jump`
 FROM participation_reports AS pr
JOIN event_data on event_data.eventID=pr.heatEventID
 WHERE pr.competitorID=32

我得到的结果是:8 8 10 8 9 0 6 7 8 17

谢谢:)

**编辑是为了将SQL更正为正确的ctrl+V :P

Answer 1

而解决方案-将是SUM () :)感谢Matt Gibson (微妙地)指出...当然，和(‘-’)将是0-因此是0....如果我从案例周围去掉SUM()，那么我就得到了我想要的:)

我使用的是我不熟悉的旧代码，所以我浏览了整个()：)

谢谢!