How to Fix 'SQLSTATE[HY093]: Invalid parameter number' Error in Multiple Inserts?

Troubleshooting Database Error: Invalid Parameter Number

The issue at hand involves an SQL query preparation error when attempting a multiple insert operation. Specifically, the error message "SQLSTATE[HY093]: Invalid parameter number: parameter was not defined" is encountered.

Upon investigation, it is evident that the number of elements in the $values and $matches arrays do not match. This discrepancy arises from the fact that $values may contain existing values prior to entering the loop. To resolve this issue, it is imperative to initialize $values as an empty array.

Additionally, it is advisable to ensure that the "hash" column has a unique index applied to it. This will prevent duplicate values from being inserted into the database.

Here is a revised code snippet that addresses these issues:

$matches = array('1');
$count = count($matches);
$values = [];
for($i = 0; $i < $count; ++$i) {
    $values[] = '(?)';
}

// INSERT INTO DATABASE
$sql = "INSERT INTO hashes (hash) VALUES " . implode(', ', $values) . " ON DUPLICATE KEY UPDATE hash=values(hash)";
$stmt = $dbh->prepare($sql);
$data = $stmt->execute($matches);

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