Are you getting the "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error when trying to execute a query in MySQL? Don't worry. This error is common among developers, and there are different ways to fix it. In this guide, we will explain what this error means and provide a step-by-step solution to fix it.
Understanding the Error
The "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error typically occurs when you pass a boolean value instead of a MySQLi result object to the mysqli_num_rows() function. This function expects a MySQLi result object as its parameter, which is returned by the mysqli_query() function when you execute a query in MySQL.
When you pass a boolean value instead of a MySQLi result object, the mysqli_num_rows() function throws the "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error.
Step-by-Step Solution
To fix the "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error, follow these steps:
Check your query: Make sure that your query is correct and returns a MySQLi result object. You can use the mysqli_query() function to execute your query and get the result object.
Store the result object: Assign the result object returned by the mysqli_query() function to a variable. This variable will be used as the parameter for the mysqli_num_rows() function.
Check the result object: Before calling the mysqli_num_rows() function, make sure that the result object is not a boolean value. You can use the PHP var_dump() function to check the type and value of the result object.
- Call the mysqli_num_rows() function: Once you have the result object, pass it as the parameter to the mysqli_num_rows() function. This function will return the number of rows in the result object.
Here's an example code snippet that demonstrates the solution:
$query = "SELECT * FROM users";
$result = mysqli_query($conn, $query);
if ($result !== false) {
// The query was successful, and $result is a MySQLi result object.
$num_rows = mysqli_num_rows($result);
echo "Number of rows: " . $num_rows;
} else {
// The query failed.
echo "Error: " . mysqli_error($conn);
}
FAQs
Q1. What is a MySQLi result object?
A MySQLi result object is a data structure returned by the mysqli_query() function when you execute a query in MySQL. This object contains the result of the query and can be used to fetch rows from the result set.
Q2. Why am I getting the "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error?
You are getting this error because you are passing a boolean value instead of a MySQLi result object to the mysqli_num_rows() function.
Q3. How can I debug this error?
You can debug this error by checking your query, storing the result object, checking the result object, and calling the mysqli_num_rows() function. You can also use the PHP var_dump() function to check the type and value of the result object.
Q4. Can I use the mysqli_num_rows() function with other database systems?
No, the mysqli_num_rows() function is specific to MySQL and cannot be used with other database systems.
Q5. How can I prevent this error from happening in the future?
To prevent this error from happening in the future, make sure that you always pass a MySQLi result object to the mysqli_num_rows() function. You can also use prepared statements to avoid SQL injection attacks and improve the security of your application.
Related Links
- PHP mysqli_num_rows() function
- PHP mysqli_query() function
- PHP var_dump() function
- PHP Prepared Statements
We hope this guide has helped you fix the "mysqli_num_rows() Expects Parameter 1 to be mysqli_result, Boolean Given In" error. If you have any questions or feedback, please let us know in the comments below.