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'.
0. The average cost to lay concrete per square foot is about $4. Prices have gone high in the past few years due to the inflation. The cost to lay concrete in the USA used to be between $1.5-$2.5 but these days it is near $4.5 or even as high as $5.It also depends on the person to whom you are giving the job for concrete.. The average cost to lay concrete per square foot is about $4. Prices have gone high in the past few years due to the inflation. The cost to lay concrete in the USA used to be between $1.5-$2.5 but these days it is near $4.5 or even as high as $5.