How can I use SUM() to sum my result array?

My current method to add the rows toge开发者_开发百科ther is like so:

$totalxp = $row['Attackxp'] + $row['Defencexp'] + $row['Strengthxp'] + $row['Hitpointsxp'] + $row['Rangedxp'] + $row['Prayerxp'] + $row['Magicxp'] + $row['Cookingxp'] + $row['Woodcuttingxp'] + $row['Fletchingxp'] + $row['Fishingxp'] + $row['Firemakingxp'] + $row['Craftingxp'] + $row['Smithingxp'] + $row['Miningxp'] + $row['Herblorexp'] + $row['Agilityxp'] + $row['Thievingxp'] + $row['Slayerxp'] + $row['Farmingxp'] + $row['Runecraftxp'] + $row['Constructionxp'];

But then I saw SUM() and I tried this:

SELECT SUM(xp) FROM skills WHERE playerName='Undercover' 

It works but I needed all the values of xp, so I tried adding %xp but it wont work.

How could I use the Sum() function to add all the rows up instead of straining PHP?

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Aggregate functions (IE: SUM, MIN, MAX, COUNT, etc) don't work across columns--they work on the values for the specific column, based on the grouping (GROUP BY) and filteration (JOIN and/or WHERE clause).

To add up values across columns, you need to add them like you would for normal mathematical equations:

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' 

If you have more than one record associated to a playername, then you can use an aggregate function:

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'

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That depend of the table data if each player is one entity (row) then is enaught to add columns:

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'

But is there more rows per player then You will need to sum also the rows

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'

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