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...
home / medterms medical dictionary a-z list / vena cava definition Medical Definition of Vena cava Vena cava: The superior vena cava is the large vein which returns blood to the heart from the head, neck and both upper limbs. The inferior vena cava returns blood to the heart from the lower part of the body. The return of blood via the vena cava can be compromised and cause disease. For example, in the superior vena cava syndrome, the symptoms that result from compression of the large vein that carries blood down to the heart.