Partial Dependency | MySmartChannels

Partial Dependency | MySmartChannels

Partial dependency is when an attribute of a table (relation) is functionally determined by one field of the primary identifier without needing the whole identifier to determine its value. In other words, an attribute that is only dependent on part of the primary identifier. For example, in a relation with the primary identifier as [Customer ID, Stock], the attribute Current Price is partially dependent on the primary key because the field Stock functionally determines Current Price alone, without needing the Customer ID to uniquely identify the current price. Therefore, Current Price should be taken out of the relation and put into another table where the primary identifier is simply Stock. In this new table, the partial dependency would be eliminated because the Current Price attribute is now dependent on the whole identifier (which is Stock), as opposed to only part of it (as before when the primary identifier was [Customer ID, Stock].

It is important to note that partial dependencies only can occur if there is more than one field making up the primary identifier/key. If there is only one field to the primary identifier, then you do not need to worry about partial dependencies. Hope this description is helpful to those who needed clearing up on the subject matter.