SQL database constraint behavior---prevent data leakage

To prevent some of the filling is not filled:
One, non-null constraints
cannot be null.
Action: Remove the check box in "Allow null values" in the table's design interface.

Second, the default value.
If you do not assign a value to the column, it will be filled with the default value.
Action: In the table's design interface, select the appropriate column in the property panel below--default value

For example, select the Name column, locate the default value in the Properties panel below, and then fill in the element that is automatically assigned when the column is not assigned a value

SQL database constraint behavior---prevent data leakage