Why Does mysqli_stmt::num_rows Return 0, and How Can I Fix It?

Understanding the Mystery of mysqli_stmt::num_rows Returning 0

In a world of dynamic database interactions, it's not uncommon to encounter problems with obtaining the correct number of rows from a MySQL query. This issue can arise specifically when using the mysqli_stmt::num_rows function.

Problem Statement: Zero Returned Value

Developers often encounter cases where the mysqli_stmt::num_rows function continuously returns 0 despite there being result rows after executing a query. This discrepancy can be quite frustrating, preventing accurate data retrieval and processing.

Solution: The Power of mysqli_stmt::store_result()

The key to solving this issue lies in understanding the behavior of mysqli_stmt::num_rows. This function does not automatically count the number of rows in the result set; rather, it returns a value based on a specific condition:

• No mysqli_stmt::store_result() Call: If the mysqli_stmt::store_result() function is not called prior to accessing mysqli_stmt::num_rows, the function will return 0, even if there are result rows.

To resolve this problem, developers must explicitly call mysqli_stmt::store_result() after executing the query and before attempting to use mysqli_stmt::num_rows. Here's an updated code snippet that incorporates this necessary step:

By incorporating mysqli_stmt::store_result(), the MySQL server is instructed to store the result set in the client-side memory, making it available for subsequent processing. This ensures that mysqli_stmt::num_rows can accurately count the number of rows in the stored result set, returning the correct value.

Conclusion

Understanding the importance of mysqli_stmt::store_result() when using mysqli_stmt::num_rows is crucial for developers working with MySQL databases. By explicitly calling mysqli_stmt::store_result(), developers can ensure that they obtain accurate row counts, empowering them to handle database data effectively and efficiently.

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