Setting MAX for Auto Increment ID in SQL Server - sql

Question

I have a table that imports 221 rows from a database table. Whenever I add a row dynamically inside the HTML Table page, I want it to be able to pull the MAX ID, so in this case 221, and add 1 to it, therefore bringing the MR_ID to 222. I need this because each ID must be unique. Whenever I add a row into the table and look at it in the database, it displays as NULL. I have a little something for that, but it doesn't seem to be working. If you need any more code than what I posted, let me know and I will provide it. Thank you!
<?php
$MR_ID = $_POST['MR_ID'];
$MR_Name = $_POST['MR_Name'];
$Buyer_ID = $_POST['Buyer_ID'];
$MR_POC_N = $_POST['MR_POC_N'];
$MR_POC_E = $_POST['MR_POC_E'];
$MR_POC_P = $_POST['MR_POC_P'];
$host="xxxxxxx";
$dbName="xxxx";
$dbUser="xxxxxxxxxxx";
$dbPass="xxxxxxxxx";
$pdo = new PDO("sqlsrv:server=".$host.";Database=".$dbName, $dbUser, $dbPass);
$MR_ID = "Select MAX(MR_ID) + 1 FROM Stage_Rebate_Master";
$sql = "INSERT INTO Stage_Rebate_Master (MR_ID, MR_Name, Buyer_ID, MR_POC_N, MR_POC_E, MR_POC_P) VALUES (?, ?, ?, ?, ?, ?)";
$stmt = $pdo->prepare($sql);
$result = $stmt->execute(array($MR_ID, $MR_Name, $Buyer_ID, $MR_POC_N, $MR_POC_E, $MR_POC_P));
echo json_encode($result);
?>

Answer 1

you can try like this
$sql = "INSERT INTO Stage_Rebate_Master (MR_ID, MR_Name, Buyer_ID, MR_POC_N, MR_POC_E, MR_POC_P) SELECT ISNULL(MAX(MR_ID)+1,1), ?, ?, ?, ?, ? FROM Stage_Rebate_Master";
$stmt = $pdo->prepare($sql);
$result = $stmt->execute(array( $MR_Name, $Buyer_ID, $MR_POC_N, $MR_POC_E, $MR_POC_P));