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'.
The price of a patio depends on the material you choose. Regular concrete costs up to $5 per square foot, while stamped concrete runs $8 to $12 per square foot. Brick costs about $7 to $8 per square foot.Concrete patio pavers cost about $10 to $20 per square foot, and natural stone costs about $15 to $30 per square foot.All prices include installation.he price of a patio depends on the material you choose. Regular concrete costs up to $5 per square foot, while stamped concrete runs $8 to $12 per square foot. Brick costs about $7 to $8 per square foot.