PHP array math, removing dublicates and addition of array rows -

PHP array math, removing dublicates and addition of array rows -

okay, trying accomplish rather simple. don't know how, , hope can help.

i have array 2 values, userid , transaction value. userid not unique, , list/array of same values, "summed up". meaning: if userid has more occurrences, 2nd value (the transaction) added together. post example.

$a = array( 1 => 1, 1 => 2, 2 => 3, 2 => -17 );

the result after running whatever function needed, is:

$a = array( 1 => 3, 2 => -14 );

so no dublicate userid's, , transaction values added 1 entry of userid.

i getting these values sql database, if can solve sql view or something, go valid reply :-)

thanks lot in advance!

in sql if columns say, id , value,

select sum(value) table_name grouping id

php arrays addition