Implementing soft deletes using an IsDeleted column involves adding a boolean column to your database table that indicates whether a record is considered deleted or not. Instead of physically removing records from the database when they are deleted, you update this column to mark the record as deleted. Here’s how you can implement soft deletes in a straightforward manner, including implementation details for both the database and application code.
Step 1: Update Your Database Schema
1. Add an IsDeleted column: First, modify your table to include a new boolean column called IsDeleted.
ALTER TABLE YourTableName ADD IsDeleted BIT NOT NULL DEFAULT 0;
Step 2: Update CRUD Operations
In your application, you'll need to adjust your Create, Read, Update, and Delete (CRUD) operations to accommodate soft deletes:
Create Operation
The Create operation remains unchanged as you simply insert a new record with IsDeleted set to 0 (false).
INSERT INTO YourTableName (Column1, Column2, IsDeleted) VALUES (Value1, Value2, 0);
Read Operation
When retrieving records, you should only fetch records where IsDeleted is 0. This can usually be accomplished by adding a condition to your SELECT queries.
SELECT * FROM YourTableName WHERE IsDeleted = 0;
For example, if you are writing ORM queries (like in Entity Framework), you might have a base repository class that handles this filtering:
public List<Entity> GetAllEntities()
{
return dbContext.Entities.Where(e => !e.IsDeleted).ToList();
}
Update Operation
The Update operation should behave as usual, allowing updates to non-deleted records. If you want to update the IsDeleted status to mark a record as deleted:
UPDATE YourTableName SET IsDeleted = 1 WHERE Id = @Id;
Delete Operation
Instead of deleting records from the database, you'd execute the update to set IsDeleted to 1:
UPDATE YourTableName SET IsDeleted = 1 WHERE Id = @Id;
Step 3: Consider Additional Features
- Restoration: Implement a method to "restore" soft-deleted records by setting IsDeleted back to 0.
UPDATE YourTableName SET IsDeleted = 0 WHERE Id = @Id;
- Hard Delete: If needed, you may also want to provide a hard delete functionality that physically removes records from the database:
DELETE FROM YourTableName WHERE Id = @Id AND IsDeleted = 1;
Step 4: Testing
Make sure to thoroughly test your implementation. Ensure that:
- You can create, read, update, and soft delete records correctly.
- You cannot read soft-deleted records unless explicitly included in your queries.
- You can restore soft-deleted records back to active.
- The hard delete functionality works as expected without affecting soft deleted records.
Final Considerations
- Indexing: For performance, consider adding an index on the IsDeleted column, especially if your table has a lot of records.
- Monitoring: Log actions when records are soft-deleted or restored for debugging and auditing purposes.
- Data Integrity: Ensure that your application logic maintains integrity and doesn't allow operations that shouldn't be performed on soft-deleted records.
By following these steps, you can effectively implement soft deletes in your application using an IsDeleted column.