使用PHP将MySQL查询嵌套到UPDATE或INSERT

Question

Using MySQL and PHP I'm making an index of the "amounts" table and grouping it by product, type, month, day, and hour. Then either updating a matching record in the "amounts_merged" table or inserting a new record if it does not already exist.

Here is the solution I came up with. But I'm not sure this is the best way to go about this. Any suggestions would be great.

$sql = "SELECT product, type, month, day, hour, AVG(amount) AS average_amount FROM amounts GROUP BY product, type, month, day, hour";
$result1 = @mysql_query($sql, $con) or die(mysql_error());

while($row = mysql_fetch_array($result1)) {

    $average_amount = $row[average_amount];
    $product = $row[product];
    $type = $row[type];
    $month = $row[month];
    $day = $row[day];
    $hour = $row[hour];

    $sql = "UPDATE amounts_merged SET average_amount = '$average_amount' WHERE product = '$product' AND type = '$type' AND month = '$month' AND day = '$day' AND hour = '$hour'";
        $result2 = @mysql_query($sql, $con) or die(mysql_error());

        $updated_rows = mysql_affected_rows();

        if ($updated_rows == 0) {

            $sql = "INSERT INTO amounts_merged (product, type, month, day, hour, average_amount)
                        VALUES ('$product', '$type', '$month', '$day', '$hour', '$average_amount')";
            $result3 = @mysql_query($sql, $con) or die(mysql_error());


    }

}

Answer 1

Add a unique key and let MySQL handle it:

ALTER TABLE amounts_merged  ADD UNIQUE (product,type,month,day,hour)

In PHP:

 $sql = "INSERT INTO amounts_merged 
    (product,type,month,day,hour,average_amount)
    SELECT product, type, month, day, hour, AVG(amount) AS average_amount
    FROM amounts
    GROUP BY product, type, month, day, hour
    ON DUPLICATE KEY UPDATE average_amount = VALUES(average_amount);"
 mysql_query($sql, $con);

Some loose remarks:

• Don't quote variables that are integers or floats (don't know if they are, but I have my suspicions...
• Prepared statements are even more handy for both running more update queries then 1, and in preventing SQL injection.
• Having seperate columns for month/date/hour in your original amounts table is probably making live harder then need be, as with just having a timestamp/datetime you can get the data easily from those fiels, and you can still use all date functions easily on the original field.