我什么时候在mysqli bind_param中使用字符串和整数

Question

I have data that is in json as follows:

[
    {
    "table":"activity",
    "activity_id":"1414676438824",
    "activity_ref":"61",
    "activity_phase":"1",
    "activity_group":"2"
    }
]

I process this using a prepared statement like this:

$statement = $mysqli->prepare("INSERT INTO activity (activity_id, activity_ref, activity_phase, activity_group) VALUES (?, ?, ?, ?)");

foreach($jsonArray as $row) {
    $statement->bind_param('siii', $row['activity_id'], $row['activity_ref'], $row['activity_group'], $row['activity_phase']);
    $statement->execute();
}

In my table, the id is BIGINT(20) (it's actually a timestamp that is useful elsewhere). The query fails when I include the id field but is successful otherwise. I've tried changing the prepared statement to use a string (s) and integer (i) but with no luck. I've tried changing, adding and removing quotes from my json.

Any ideas?