- Verify the query syntax and ensure that the table name and conditions in the WHERE clause are correct. Make sure you're querying the correct database.
- Check if the record actually exists:
SELECT * FROM yourtablename WHERE your_condition;
- Ensure that the database user has the correct permissions to read the table:
SHOW GRANTS FOR CURRENT_USER;
- Check for any active transactions that might have locked the table or row:
SHOW OPEN TABLES WHERE In_use > 0;
- Look for any recent changes in the table schema that might affect the query:
SHOW TABLE STATUS LIKE 'yourtablename';
- If using replication, ensure that the slave is up to date with the master:
SHOW SLAVE STATUS\G
- Examine the MySQL error log for any additional clues:
tail -f /var/log/mysql/error.log
- Make sure the database is not in a read-only mode, which could prevent updates:
SHOW VARIABLES LIKE 'read_only';
9. Confirm there are no network issues affecting connectivity to the database.
