So this is my first big step into php and I am somewhat stuck.

I keep getting:

Error: INSERT INTO `MyTable` (`buildInfo`) VALUES ('["name1", "name2", "name3"]') ON DUPLICATE KEY UPDATE<br>You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

but if I run this on mySql server it runs fine:

INSERT INTO `MyTable` (`buildInfo`)
VALUES ('["name1", "name2", "name3"]')

this is my PHP:

<?php
$servername = "oatney.cauldron.dreamhost.com";
$username = "Me";
$password = "MyPassword";
$dbname = "Database_Name";

$conn = new mysqli($servername, $username, $password, $dbname); // Create connection
if ($conn->connect_error) {     // Check connection
die("Connection failed: " . $conn->connect_error);
} 

$build = mysqli_real_escape_string($conn, $_POST['build']);

if (strlen($times) > 200000) {  $times = "";    }

$sql = "INSERT INTO `MyTable` (`buildInfo`) VALUES ('[\"name1\", \"name2\", \"name3\"]') ON DUPLICATE KEY UPDATE";

if ($conn->query($sql) === TRUE) {
echo "Page saved!";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>

and this is my JS call:

saveBuild('SaveBuild.php', '{"age": 30, "city": "New York", "name": "John"}').then(function(response) {
console.log(response);
});

function saveBuild(url, build){

 return new Promise(function(resolve, reject) {
// Do the usual XHR stuff
var req = new XMLHttpRequest();

req.open('POST', url, true);
req.setRequestHeader('Content-Type', 'application/json;charset=UTF-8'); //-Name and value, one row for each

req.onload = function() {
  // This is called even on 404 etc
  // so check the status
  if (req.status == 200) {
    // Resolve the promise with the response text
    resolve(req.response);
  }
  else {
    // Otherwise reject with the status text
    // which will hopefully be a meaningful error
    reject(Error(req.statusText));
  }
};



// Handle network errors
req.onerror = function() {
  reject(Error("Network Error"));
};

// Make the request
req.send('build=aaa'   JSON.stringify({"age": "30", "city": "New York", "name": "John"}));
  });
}

Any suggestions as to what I am doing wrong?