Dominoes Dominoes Dominoes is a family of tile-based games played with rectangular "domino" tiles. Each domino is a rectangular tile with a line dividing its face into two square "ends". Each end is marked with a number of spots (also called "pips", "nips", or "dobs") or is blank. The backs of the dominoes in a set are indistinguishable, either blank or having some common design. The domino gaming pieces make up a domino set, sometimes called a "deck" or "pack". The traditional Sino-European domino set consists of 28 dominoes, featuring all combinations of spot counts between zero and six. A domino
Unique identifier Unique identifier With reference to a given (possibly implicit) set of objects, a unique identifier (UID) is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. There are three main types of unique identifiers, each corresponding to a different generation strategy: The above methods can be combined, hierarchically or singly, to create other generation schemes which guarantee uniqueness. In many cases, a single object may have more than one unique identifier, each of which identifies it for a different purpose. In relational databases, certain attributes of an entity that