如何使用sum()对结果数组求和?

聚合函数(例如:SUM、MIN、MAX、COUNT等)不跨列工作——它们基于分组处理特定列的值。( GROUP BY )和过滤( JOIN 和/或 WHERE 条款)。

要跨列添加值,需要像对普通数学公式那样添加它们:

SELECT Attackxp + Defencexp + Strengthxp + Hitpointsxp + Rangedxp + Prayerxp + Magicxp + Cookingxp+ Woodcuttingxp + Fletchingxp + Fishingxp + Firemakingxp + Craftingxp + Smithingxp + Miningxp + Herblorexp + Agilityxp + Thievingxp + Slayerxp + Farmingxp + Runecraftxp + Constructionxp AS total_xp
  FROM skills 
 WHERE playerName = 'Undercover' 

如果有多个记录与一个playername关联, 然后 您可以使用聚合函数:

SELECT SUM(Attackxp + Defencexp + Strengthxp + Hitpointsxp + Rangedxp + Prayerxp + Magicxp + Cookingxp+ Woodcuttingxp + Fletchingxp + Fishingxp + Firemakingxp + Craftingxp + Smithingxp + Miningxp + Herblorexp + Agilityxp + Thievingxp + Slayerxp + Farmingxp + Runecraftxp + Constructionxp) AS total_xp
  FROM skills 
 WHERE playerName = 'Undercover'

这取决于表数据,如果每个播放器是一个实体(行),则需要添加列:

SELECT Attackxp  + Defencexp + Strengthxp + Hitpointsxp +Rangedxp + Prayerxp + Magicxp + Cookingxp + Woodcuttingxp + Fletchingxp + Fishingxp + Firemakingxp + Craftingxp + Smithingxp + Miningxp + Herblorexp + Agilityxp + Thievingxp + Slayerxp + Farmingxp + Runecraftxp + Constructionxp 
As totalSkills FROM skills WHERE playerName = 'Undercover'

但是每个玩家是否有更多的行,那么你还需要把这些行加起来

SELECT SUM(Attackxp  + Defencexp + Strengthxp + Hitpointsxp +Rangedxp + Prayerxp + Magicxp + Cookingxp + Woodcuttingxp + Fletchingxp + Fishingxp + Firemakingxp + Craftingxp + Smithingxp + Miningxp + Herblorexp + Agilityxp + Thievingxp + Slayerxp + Farmingxp + Runecraftxp + Constructionxp) 
As totalSkills FROM skills WHERE playerName = 'Undercover'

SELECT SUM(`Attackxp`) + SUM(`Defencexp`) + ... AS `total_sum`
  FROM skills
 WHERE playerName='Undercover'