Search results
Results from the WOW.Com Content Network
For referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table's primary key or a candidate key. [2] In other words, when a foreign key value is used it must reference a valid, existing primary key in the parent table. For ...
Entity integrity is concerned with ensuring that each row of a table has a unique and non-null primary key value; this is the same as saying that each row in a table represents a single instance of the entity type modelled by the table. A requirement of E. F. Codd in his seminal paper is that a primary key of an entity, or any part of it, can ...
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
The extracted relations are amended with foreign keys referring to the primary key of the relation which contained it. The process can be applied recursively to non-simple domains nested in multiple levels. [4] In this example, Customer ID is the primary key of the containing relations and will therefore be appended as foreign key to the new ...
C-sharp musical note. The name "C sharp" was inspired by the musical notation whereby a sharp symbol indicates that the written note should be made a semitone higher in pitch. [38] This is similar to the language name of C++, where "++" indicates that a variable should be incremented by 1 after being evaluated.
Visual Studio Tools for Office is a SDK and an add-in for Visual Studio that includes tools for developing for the Microsoft Office suite. Previously (for Visual Studio .NET 2003 and Visual Studio 2005) it was a separate SKU that supported only Visual C# and Visual Basic languages or was included in the Team Suite.
Surrogate key. A surrogate key (or synthetic key, pseudokey, entity identifier, factless key, or technical key[citation needed]) in a database is a unique identifier for either an entity in the modeled world or an object in the database. The surrogate key is not derived from application data, unlike a natural (or business) key.
Spec#. Spec# is a dialect of C# that is developed in parallel with the standard implementation from Microsoft. It extends C# with specification language features and is a possible future feature to the C# language. It also adds syntax for the code contracts API that was introduced in .NET Framework 4.0.