Automatically Update a Date Modified Field

To achieve this functionality in SQL Server, you can create a trigger that automatically updates the date field whenever a row is changed (updated) in a specific table. Here's an example of how to create such a trigger:

Assuming you have a table named "YourTable" with a column named "ModifiedDate" that you want to update whenever a row is modified:

1. Create the trigger:

```sql
CREATE TRIGGER tr_UpdateModifiedDate
ON YourTable
AFTER UPDATE
AS
BEGIN
    SET NOCOUNT ON;
    UPDATE YourTable
    SET ModifiedDate = GETDATE()
    FROM YourTable
    INNER JOIN inserted ON YourTable.PrimaryKeyColumn = inserted.PrimaryKeyColumn;
END;
```

Replace "YourTable" with the actual name of your table and "PrimaryKeyColumn" with the primary key column of your table.

2. Explanation:

- The `AFTER UPDATE` clause specifies that the trigger will fire after an update operation is performed on the table.

- The `inserted` table is a special table available inside triggers that contains the updated rows during an update operation.

- The `INNER JOIN inserted` is used to match the rows in the "YourTable" with the updated rows from the "inserted" table based on the primary key column.

- `ModifiedDate = GETDATE()` will update the "ModifiedDate" column to the current date and time (using `GETDATE()`) for the rows that were changed.

With this trigger in place, whenever a row is updated in "YourTable," the "ModifiedDate" column for that specific row will be automatically updated to the current date and time.