How to Fix 'Invalid Parameter Number' Errors in MySQL Multiple INSERT Queries?

Resolving the "Invalid Parameter Number" Error in Multiple Insert Queries

In the provided code, the error arises when executing a multiple insert query due to a parameter mismatch between the values being inserted and the expected number of parameters in the query.

Understanding the Problem

The code generates an array of placeholders ($values) based on the count of matches ($matches). However, if there's already content in the $values array, it can lead to a discrepancy in counts, causing the error.

Solution

To address this issue:

• Always initialize the $values array to an empty state before using it in the loop.

  $values = [];

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• Ensure that the hash column in the database has a unique index, which is essential for the correct functioning of the query.

Revised Code

$matches = array('1');
$count = count($matches);
$values = [];

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

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

By implementing these changes, the code should execute successfully without encountering the parameter mismatch error.

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