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'.
What is The Average Cost of Concrete Slabs Per Square Foot. The cost of concrete slabs will vary depending upon the size and depth of the slab as well as other factors. The average cost of a concrete slab will be between $5 and $7 dollars per square foot or $135 and $189 per cubic yard. Once the slab size is determined, then it is time to calculate the amount of concrete that will be needed. Concrete is sold per cubic yard which is 27 square feet.