If you are a developer who uses PHP and MySQL in your projects, you may have encountered the error message "Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in" at some point. This error occurs when you try to fetch data from a MySQL database using the mysqli_fetch_array() function, but the query returns a boolean value instead of a result set.
In this comprehensive guide, we will discuss the root cause of this error and provide step-by-step instructions on how to fix it. We'll also include an FAQ section with common questions about this error.
What Causes the 'mysqli_fetch_array() Expects Parameter 1 to be mysqli_result, Boolean Given In' Error?
This error is caused by a simple mistake in your PHP code. When you execute a query using the mysqli_query() function, it returns either a result set or a boolean value. If the query fails, it returns false, which is a boolean value. If you try to fetch data from this boolean value using the mysqli_fetch_array() function, you will get the "mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in" error.
How to Fix the 'mysqli_fetch_array() Expects Parameter 1 to be mysqli_result, Boolean Given In' Error
To fix this error, you need to check whether the mysqli_query() function returned a result set or a boolean value. You can do this by using the mysqli_num_rows() function to check if there are any rows returned by the query.
Here are the steps to fix the 'mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in' error:
- Replace the mysqli_query() function with the following code:
$query = mysqli_query($connection, $sql);
if (!$query) {
die('Query failed: ' . mysqli_error($connection));
}
if (mysqli_num_rows($query) > 0) {
// Fetch data using mysqli_fetch_array() function
} else {
// Handle no rows returned
}
The code above checks if the query was successful using the mysqli_query() function. If it failed, it will display the error message using the mysqli_error() function.
The code then checks if the query returned any rows using the mysqli_num_rows() function. If there are rows, you can fetch the data using the mysqli_fetch_array() function. If there are no rows, you can handle the situation as needed.
FAQ: Common Questions About the 'mysqli_fetch_array() Expects Parameter 1 to be mysqli_result, Boolean Given In' Error
Q1: What is the difference between mysqli_fetch_array() and mysqli_fetch_assoc()?
A1: The mysqli_fetch_array() function returns an array of both numeric and associative keys, while the mysqli_fetch_assoc() function only returns an array with associative keys.
Q2: Can I use mysqli_fetch_array() with a boolean value?
A2: No. The mysqli_fetch_array() function requires a result set returned by the mysqli_query() function.
Q3: How do I know if my query returned a boolean value?
A3: You can check the return value of the mysqli_query() function. If it returns false, it means the query failed and returned a boolean value.
Q4: Is there a way to avoid the 'mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in' error?
A4: Yes, you can avoid this error by checking if the mysqli_query() function returned a result set or a boolean value before using the mysqli_fetch_array() function.
Q5: How can I debug my PHP code if I encounter this error?
A5: You can use the error reporting functions in PHP to help you debug your code. You can enable error reporting by adding the following code to the top of your PHP script:
ini_set('display_errors', 1);
error_reporting(E_ALL);