Why Does PHP Throw a 'Cannot Pass Parameter 2 by Reference' Error in `bind_param()`?

PHP Error: "Cannot Pass Parameter 2 by Reference"

The error indicates that the second argument passed to the bind_param() method of the $update prepared statement must be a reference to a variable. However, in the code provided, you're passing a literal integer (0) instead of a variable.

How to Fix the Error

To resolve the error, you need to pass a reference to a variable as the second argument to bind_param(). Here's the modified code:

$a = 0;
$update->bind_param("is", $a, $selectedDate); // Line 13

By assigning the integer value to the variable $a and passing $a as the second argument, you create a reference to the variable. When you update the value of $a, it will also update the value of the bound parameter in the prepared statement.

Understanding the Error

The error arises because the bind_param() method expects the second argument to be a reference to a variable so that it can bind the variable's value to the parameter in the prepared statement. Passing a literal value, like an integer, does not create a reference, hence the error.

For a more in-depth understanding of parameter binding and references in PHP, please refer to the documentation: http://php.net/manual/en/language.references.pass.php.

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