Before you can enter any data into a database table, you must design the table. It is important to think carefully about the original design of a database. After the database has been created and data has beenentered, it could be difficult and time consuming to make changes. At minimum, designing a table requires that you choose columns for it and then provide names and data types for each column.PTS:1REF:558TOP:Critical Thinking2.Discuss the use of null values within a database table.ANS:Unassigned variables within computer programs might be empty (containing a null value), or might contain unknown or garbage values. Similarly, columns in database tables might also contain null or unknown values. When a field in a database contains a null value, it does not mean that the field holds a 0 or a space; it means that no data has been entered for the field at all. Although nulland emptyare used synonymously by many database developers, the terms have slightly different meanings to some professionals, such as Visual Basic programmers.PTS:1REF:559TOP:Critical Thinking3.List two examples of primary keys.4.List three reasons why a primary key is important.