| INSERT data unsuccessful |
Ensure that the value for any primary key is unique before insertion. You can use the INSERT IGNORE or ON DUPLICATE KEY UPDATE syntax to handle duplicates gracefully. |
| DELETE data unsuccessful |
This can occur when trying to delete a row that a foreign key in another table references, without addressing the dependent data. Resolve this by setting up foreign key constraints with ON DELETE CASCADE for cascading deletes (be cautious as this automatically deletes dependent records). |
| Unexpected or missing results in JOIN |
Ensure the join condition is correct and the appropriate join type (e.g., INNER JOIN, LEFT JOIN) is used for your query logic. Check that data types of joined fields are compatible. Adjust join type or conditions as needed to match expected results. |
| TRIGGER does not fire |
Verify that the trigger is correctly defined, including correct table and event timing (BEFORE or AFTER). Ensure necessary permissions for creating and executing triggers. |
| Denial of unsafe UPDATE / DELETE |
This issue arises when you perform an UPDATE or DELETE operation without a WHERE clause, or when your WHERE clause does not reference a key column. To bypass this safety feature, you can disable it by executing SET SQL_SAFE_UPDATES = 0;. Be mindful of the associated risks and make sure to re-enable the safety feature by setting SQL_SAFE_UPDATES back to 1 after completing your operation. |
| Data Type Mismatch |
Validate and ensure that all data being inserted or updated matches the column's data type specifications. Use proper data conversion or casting as necessary. |