Question

I have a table table1 with columns id and name. I also have a table table2 with columns table1_id and num. What I’m looking to do is get a php array that holds an associative array with name and the sum of the corresponding num. Right now I’m trying a foreach loop to cycle through table1’s ids and perform an inner join. How do I do this?

Answer 1

For the query, you can use a JOIN with a subquery that groups table2 by table1_id, and calculates the sum using GROUP BY. To get the data into a associative array, use mysql_fetch_assoc:

$sql = "SELECT t.id, t.name, g.SumNum
    FROM table1 t
      LEFT JOIN (
        SELECT table1_id, SUM(num) SumNum
        FROM table2
        GROUP BY table1_id 
      ) g ON t.id = g.table1_id";

$result = mysql_query($sql);

while ($row = mysql_fetch_assoc($result)) {
    echo $row["id"];
    echo $row["name"];
    echo $row["SumNum"];
}

mysql_free_result($result);