MySQL 一行 select 只有一列没有 NULL 值

Question

    SELECT r.id AS Id, r.slot AS Slot, rg.name AS Grade, rt.name AS Type,
    r.main_stat AS Main Stat, r.stat01 AS 1st Substat, r.stat02 AS 2nd Substat,
    r.stat03 AS 3rd Substat, r.stat04 AS 4th Substat,
    CASE WHEN r.isEquipted = 0 THEN 'FALSE' ELSE 'TRUE' END AS isEquipted      
    FROM runes r                                                                           
    INNER JOIN rune_grade rg                                                                  
    ON r.grade_id = rg.id                                                                  
    INNER JOIN rune_type rt                                                                   
    ON r.type_id = rt.id                                                                    
    WHERE r.id = 7;

我有这个查询，它只给了我一条记录。 WHERE 子句中的“7”在我的代码中是可变的。我想删除给我 NULL 值的列。此查询 returns:

ID Slot Grade Type M Stat 1st Stat 2nd Stat 3rd Stat 4th Stat

7 4 normal swift spd-24 NULL NULL NULL NULL

如果Where子句等于其他id，则1st 2nd 3rd 4th Stat可以有值。

ID Slot Grade Type M Stat 1st Stat 2nd Stat 3rd Stat 4th Stat

6 3 normal swift spd-24 atk-32 hp-355 NULL NULL

抱歉英语不好.. <3

Answer 1

使用COALESCE()过滤掉所有[X Stat]列为NULL:

的行

WHERE r.id = 7 
  AND COALESCE(r.stat01, r.stat02, r.stat03, r.stat04) IS NOT NULL

MySQL 一行 select 只有一列没有 NULL 值

MySQL One row select only column without NULL values

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