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'.
Does anyone know what's a decent price per square foot for a concrete patio? Nothing fancy - just a 10'x20' concrete slab with a broom finish. I know people last year who paid <$5 per square foot and so far the best I've found is $7.30 per square foot. Have prices for concrete gone up that much the past year?