Why Did Mismatched Variables and Parameters Cause an Error in mysqli Prepared Statements?

mysqli: "Number of Variables Doesn't Match Number of Parameters"

In response to the issue faced while using mysqli's prepared statements, the root cause lies in the incorrect syntax of the prepared statement. As mentioned in the response, the following correction resolves the issue:

$stmt = $mysqli->prepare(
    "SELECT DISTINCT model FROM vehicle_types WHERE year = ? AND make = ? ORDER by model"
);
$stmt->bind_param('is', $year, $make);
$stmt->execute();

When preparing a statement, it is crucial to enclose placeholders for input data with question marks. However, within the original statement, the placeholder for the make variable was enclosed within quotes, rendering it unrecognizable as a placeholder. Consequently, the number of question marks mismatched the number of variables in bind_param().

Therefore, the corrected prepared statement eliminates this discrepancy by removing the quotes around the ? placeholder, which allows for the proper binding of input variables using bind_param(). This ensures that the statement can be executed successfully, producing the desired results.

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