Sep 19, 2018

Data is organized in a relational database as tables—two-dimensional matrices made up of columns and rows.

A table’s primary key, enforced by a primary key constraint is a column or combination of columns that ensures that every row in a table is uniquely identified. 

Two tables that have a common column are said to have a relationship between them; the common column is the foreign key in one table and the primary key in the other. The value (if any) stored in a row/column combination is a data element.