Deletion of rows in the data table containing references to related tables should be dealt with precaution in order to prevent inconsistencies. Initially, when one wants to delete a row, it is important to determine whether the row links to another table through a foreign key. Deletion without accommodating checks is one of the worst things that can happen, there are usually constraint violations resulting in broken relationships within the database structure. Thus, dependency is the first thing that needs to be grasped.
After identifying the dependencies, you have to decide whether you would like to drop child table entries first or alter the database constraints. In most practical cases, data in the reference, or child table, has to be first deleted before the records in the main or parent table. This writing prevents such circumstances where the foreign key constraints may be violated and therefore keeps the operations running as expected.
The two main approaches to this aspect are manual deletion and cascading deletion. Manual deletion requires that you locate the dependent rows individually and erase them separately. The second one, which is the cascading deletion, holds the capability for the database to delete the related records corresponding to the key of the parent row. Cascading is helpful to reduce the amount of time taken from the process but should be carefully applied in order to avoid loss of a lot of data.
Performing manual deletion can be slightly tricky and that’s why it is important to come up with accurate SQL queries when performing this function. First of all, dependent data should always be deleted first in order to avoid the creation of an orphaned record. This is because if one is not careful with the where conditions in your queries, more than the needed rows are selected. The manual deletion policy helps to avoid accidental deletion of important data by minimizing the impact of errors made when using the function.
Lastly, after the process of deletion, it is recommendable to check and verify the contents of your database. Ensure the remaining data is still coherent and ensure that no reference that should have been made has been lost. To enforce a level of security the database is always copied before any deletion to prevent possible mistakes from damaging the data that is stored.
Conclusion
In conclusion, Deleting rows with reference table data should be approached carefully, considering all the steps and ensuring a good knowledge of the database relationships. Again, it does not matter if you go for the manual deletion approach or cascading approach, the important thing that you should consider here is that you ensure that data integrity is achieved in the course of those deletions. It is recommended that data of the database is always backed up, queries run are properly written and executed and results checked so as to keep the database accurate, reliable and fully functional.
