Can not insert php data to mysql using for() - php

Question

i try to insert the data with php to mysql by checking the value if it exists then it will update if no then it will insert, but it fail i use for () what is wrong with my script?
if(isset($_POST['submit'])){
$fieldA = $_POST['fieldA'];
$fieldB = $_POST['fieldB'];
$fieldC = $_POST['fieldC'];
$fieldD = $_POST['fieldD'];
if (empty($fieldA)) {
echo 'fieldA cannot empty';
}
else
{
for ($i=1; $i<= $nomer; $i++) {
$query = mysql_query("SELECT * FROM tb1 ".
"WHERE fieldA = '$fieldA' ".
"AND fieldB = '$fieldB' ".
"AND fieldC = '$fieldC' ".
"AND fieldD = '$fieldD'");
$get1 = mysql_fetch_assoc($query);
$get2 = mysql_num_rows($query);
if ($get2 != 0) {
mysql_query("UPDATE tb1 SET kd_kelas = '2' ".
"WHERE fieldA = '$fieldA' ".
"AND fieldB = '$fieldB' ".
"AND fieldC = '$fieldC' ".
"AND fieldD = '$fieldD'");
} else {
mysql_query("INSERT INTO tb1(fieldA, fieldB, ".
"fieldC, fieldD) VALUES ".
"('$fieldA', '$fieldB', ".
"'$fieldC', '$fieldD')");
}
}
}
//re-direct
$go = "mydata.php";
redirect($go);
}

Answer 1

All the methods related with mysql_* is deprecated now. Use mysqli_*.
And try this snippet:
if (isset($_POST['submit']) && !empty($_POST['fieldA'])) {
$fieldA = $_POST['fieldA'];
$fieldB = $_POST['fieldB'];
$fieldC = $_POST['fieldC'];
$fieldD = $_POST['fieldD'];
for ($i = 1; $i <= $nomer; $i++) {
$sql = sprintf("SELECT * FROM tb1 WHERE fieldA = '%s' AND fieldB = '%s' AND fieldC = '%s' AND fieldD = '%s'",
$fieldA, $fieldB, $fieldC, $fieldD);
$result = mysqli_query($link, $sql);
if (mysqli_num_rows($result) > 0) {
$updateSql = sprintf("UPDATE tb1 SET kd_kelas = '2' WHERE fieldA = '%s' AND fieldB = '%s' AND fieldC = '%s' AND fieldD = '%s'",
$fieldA, $fieldB, $fieldC, $fieldD);
mysqli_query($link, $updateSql);
}
else {
$insertSql = sprintf("INSERT INTO tb1(fieldA, fieldB,fieldC, fieldD) VALUES ('%s','%s','%s','%s')", $fieldA,
$fieldB, $fieldC, $fieldD);
mysqli_query($link, $insertSql);
}
}
//re-direct
$go = "mydata.php";
redirect($go);
}
here $link is the connection string
$link = mysqli_connect('localhost', 'root', 'password', 'database');