A primary key is a candidate key that is most appropriate to be the main reference key for the table. As its name suggests, it is the primary key of reference for the table and is used throughout the database to help establish relationships with other tables.
1 A concrete driveway with several decorative elements can cost $12 -$18 a square foot, or $3,600 -$5,400 for 12'x25' or $11,500 -$17,500 for 24'x40'.
Concrete Pavers are a manufactured product, they tend to be priced between $5-$10 per sq/ft. This is a very reasonable price, particularly when compared to the higher prices of Natural Stone; however small maintenance costs must be considered. They can usually be installed for between $5-$10 per sq/ft.