Key Fields in a Database. Keys are crucial to a table structure for many reasons, some of which are identified below: 1  They ensure that each record in a table is precisely identified.  They help establish and enforce various types of integrity.
avifauna definition: The definition of avifauna are the birds that live in a certain place or at a certain time. (noun) An example of avifauna is penguins living primarily in Antarctica. An example of avifauna is the moa of New Zealand becoming extin...
Noun. 1. vena cava-either of two large veins that return oxygen-depleted blood to the right atrium of the heart. vein, vena, venous blood vessel-a blood vessel that carries blood from the capillaries toward the heart; all veins except the pulmonary vein carry unaerated blood.. vena cava-either of two large veins that return oxygen-depleted blood to the right atrium of the heart. vein, vena, venous blood vessel-a blood vessel that carries blood from the capillaries toward the heart; all veins except the pulmonary vein carry unaerated blood.