CODEWITHSUNDEEP
phpmysql
TGO
TGO

Reputation: 216

Increment a variable with the previous ones

I try to show a curve with energy produced for a day. So the curve must always be growing.

I try to increment the variable "energie_journ" my mysql database with all previous.

Exemple:

Mysql:

ID           energie_journ
1                 5
2                 5
3                 10
4                 6

Desired result:

First energie_journ = 1, the second = 10 (5 +5), third = 20 (5 +5 +10), fourth = 26 (5 +5 +10 +6).

Bit php:

while   ($row2  =   mysql_fetch_array($result2)) {
    extract($row2);

    $datetime *= 1000;

    $encode_energie_journ[] = array((float)$datetime, (float)$energie_journ == null ? null : (float)$energie_journ);
}

Thanks.

Upvotes: 2

Views: 120

Answers (3)

Ed Gibbs
Ed Gibbs

Reputation: 26363

You can also have MySQL calculate this for you:

SELECT
  ID,
  energie_journ,
  @subtot := @subtot + val AS energie_journ_to_date
FROM myTable, (SELECT @subtot := 0) subtots
ORDER BY ID;

The result will look like this:

ID      energie_journ   energie_journ_to_date
 1             5                  5
 2             5                 10
 3            10                 20
 4             6                 26

Upvotes: 1

M Khalid Junaid
M Khalid Junaid

Reputation: 64496

here you go i have made the sum of previous values in the query 

SELECT id,(SELECT SUM(energie_journ) FROM `table` WHERE `id` <= p.`id`) AS  sum_col FROM `table` p

just use the result of sum_col which i thinks is as per your needs

hope this makes sense

Upvotes: 1

alexis
alexis

Reputation: 50220

Try it like this:

$energy_journ = 0;
while   ($row = mysql_fetch_array($result2)) {
    $energy_journ += $row[1];
    // now save this value to an array, if that's what you are after.
}

And avoid using extract, it's going to give you headaches.

Upvotes: 1

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