Why is My MySQLi `bind_param()` Function Throwing a 'Call to a Member Function on a Non-Object' Error?

Mysqli Update Throwing Call to a Member Function bind_param() Error

Problem:

MySQLi is throwing a "Call to a member function bind_param() on a non-object" error when attempting to update columns in a table using the bind_param() method.

Cause:

The bind_param() method can only be called on a valid mysqli_stmt object. The error occurs because the mysqli_stmt object is not being created properly.

Solution:

To resolve this error:

1. Check the SQL Query: Verify that the SQL query in the prepare() method is syntactically correct.
2. Wrap Calls in try/catch: Encapsulate the prepare() call in a try/catch block to handle any exceptions.
3. Check for Errors: After executing the prepare() call, use $mysqli->error to check for any error messages.
4. Use PDO: Consider using PDO (PHP Data Objects) instead of MySQLi. PDO provides a more object-oriented interface and simplifies database operations.

Example with PDO:

<?php
try {
  // Create PDO connection
  $pdo = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');

  // Prepare update statement
  $stmt = $pdo->prepare("UPDATE questionnaire SET $key = ? WHERE id = ?");

  // Bind parameters
  $stmt->bindParam(1, $value, PDO::PARAM_STR); // Set the value parameter
  $stmt->bindParam(2, $rowid, PDO::PARAM_INT); // Set the rowID parameter

  // Execute update
  $stmt->execute();
} catch (PDOException $e) {
  trigger_error($e->getMessage(), E_USER_ERROR);
}

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