totaal optelling van 1 kolom in een DB table
ik probeer een totaal optelling te maken van 1 kolom binnen een Database table
hiervoor gebruik ik onderstaande code:
Code (php)
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$mysqli = new mysqli("localhost", $username, $password, $my_db);
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$sql = "SELECT SUM(payment_amount) FROM josvg_eb_registrants";
$result = mysqli_query($conn, $sql);
while($row = mysqli_fetch_assoc($result)) {
echo "Total:" . $row['SUM(payment_amount)'];
}
/* free result set */
$result->free();
/* close connection */
$mysqli->close();
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$sql = "SELECT SUM(payment_amount) FROM josvg_eb_registrants";
$result = mysqli_query($conn, $sql);
while($row = mysqli_fetch_assoc($result)) {
echo "Total:" . $row['SUM(payment_amount)'];
}
/* free result set */
$result->free();
/* close connection */
$mysqli->close();
dit levert onderstaande foutmelding op:
mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given
wie helpt mij op weg.
Grtz Manfred
Code (php)
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<?php
$mysqli = new mysqli("localhost", $username, $password, $my_db);
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$sql = "SELECT SUM(payment_amount) sum_payment_amounts FROM josvg_eb_registrants";
$result = mysqli_query($mysqli, $sql);
echo "Total:" . $result->fetch_object()->sum_payment_amounts;
$result->free();
$mysqli->close();
?>
$mysqli = new mysqli("localhost", $username, $password, $my_db);
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$sql = "SELECT SUM(payment_amount) sum_payment_amounts FROM josvg_eb_registrants";
$result = mysqli_query($mysqli, $sql);
echo "Total:" . $result->fetch_object()->sum_payment_amounts;
$result->free();
$mysqli->close();
?>