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...
From Wikipedia, the free encyclopedia. The superior vena cava (also known as the cava or cva) is a large diameter (24 mm), yet short, vein that carries deoxygenated blood from the upper half of the body to the heart 's right atrium.It is located in the anterior right superior mediastinum.rom Wikipedia, the free encyclopedia. The superior vena cava (also known as the cava or cva) is a large diameter (24 mm), yet short, vein that carries deoxygenated blood from the upper half of the body to the heart 's right atrium.