Why is my PHP code throwing a 'Warning: mysql_fetch_array(): Supplied Argument is Not a Valid MySQL Result' error?

Warning: mysql_fetch_array(): Supplied Argument is Not a Valid MySQL Result

Problem:

The error message "Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result [duplicate]" indicates an issue with accessing the results of a database query.

Investigation:

To troubleshoot this error, follow these steps:

1. Check the Database Connection: Ensure that the DbConnector class is correctly initialized and connecting to the database.
2. Verify the Query: Check the syntax of the SQL query being executed in the $result = $connector->query('SELECT ...') line. Ensure that the query is valid and returns a result set.
3. **Inspect mysql_error(): After executing the query, check for any errors using mysql_error(). This will provide additional information about the cause of the failure.
4. Review the fetchArray Function: The fetchArray function in the DbConnector class is responsible for extracting an array of results from the query. Check if the $result argument is a valid resource representing the query results.

Solution:

Based on the investigation, the most likely cause is an issue with the query itself. Check for any typographical errors or logical inconsistencies that may prevent the query from executing correctly. Alternatively, if the query is large or complex, consider using prepared statements to avoid injection vulnerabilities.

Additionally, using the modified version of the query function in the DbConnector class as suggested in the answer can help by throwing an exception with specific error information in case of invalid queries. This will make troubleshooting issues easier in the future.

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