A unit of work is a behavioral pattern in software development. Martin Fowler has defined it as everything one does during a business transaction which can affect the database. When the unit of work is finished it will provide everything that needs to be done to change the database as a result of the work.

A unit of work encapsulates one or more code repositories[de] and a list of actions to be performed which are necessary for the successful implementation of self-contained and consistent data change. A unit of work is also responsible for handling concurrency issues, and can be used for transactions and stability patterns.[de]

See also 
 ACID (atomicity, consistency, isolation, durability), a set of properties of database transactions
 Database transaction, a unit of work within a database management system
 Equi-join, a type of join where only equal signs are used in the join predicate
 Lossless join decomposition, decomposition of a relation such that a natural join of the resulting relations yields back the original relation

References 

Software engineering