mysqli Query Preparation with Multiple Queries

Multi-query preparation is not supported by mysqli's prepared statement feature. A prepared statement in mysqli is limited to executing a single MySQL query.

Alternative Approach:

If you need to execute multiple queries in sequence, you can create separate prepared statements for each query:

$stmtUser = $sql->prepare("INSERT INTO user (id_user, username, pw, email) VALUES (?,?,?,?)");
$stmtProc = $sql->prepare("INSERT INTO process (id_user, idp) VALUES (?,?)");

Transaction-Based Approach:

Alternatively, you can use transactions to ensure that either both queries are executed or neither is executed:

$sql->begin_transaction();

// Execute both queries

if (!$stmtUser->execute() || !$stmtProc->execute()) {
    $sql->rollback();
} else {
    $sql->commit();
}

Error Debugging:

If you encounter an "call to member function on a non-object" error, it indicates that the preparation of the statement failed. Check your prepare() statement carefully for any errors.