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A data dependency in computer science is a situation in which a program statement (instruction) refers to the data of a preceding statement. In compiler theory , the technique used to discover data dependencies among statements (or instructions) is called dependence analysis .
A database abstraction layer (DBAL [1] or DAL) is an application programming interface which unifies the communication between a computer application and databases such as SQL Server, IBM Db2, MySQL, PostgreSQL, Oracle or SQLite. Traditionally, all database vendors provide their own interface that is tailored to their products.
Every non-trivial functional dependency begins with a superkey (a stricter form of 3NF) — Every non-trivial multivalued dependency begins with a superkey — Every join dependency has a superkey component [8] — Every join dependency has only superkey components — Every constraint is a consequence of domain constraints and key constraints
In object-oriented design, the dependency inversion principle is a specific methodology for loosely coupled software modules.When following this principle, the conventional dependency relationships established from high-level, policy-setting modules to low-level, dependency modules are reversed, thus rendering high-level modules independent of the low-level module implementation details.
In SQL Server versions 6.5 and earlier, database administrators (DBAs) used SQL Server Transfer Manager and Bulk Copy Program, included with SQL Server, to transfer data. These tools had significant shortcomings, and many [ quantify ] DBAs used third-party tools such as Pervasive Data Integrator to transfer data more flexibly and easily.
A set S of functional dependencies is irreducible if the set has the following three properties: Each right set of a functional dependency of S contains only one attribute. Each left set of a functional dependency of S is irreducible. It means that reducing any one attribute from left set will change the content of S (S will lose some information).
A trivial multivalued dependency X Y is one where either Y is a subset of X, or X and Y together form the whole set of attributes of the relation. A functional dependency is a special case of multivalued dependency. In a functional dependency X → Y, every x determines exactly one y, never more than one.
In this different sense, "inversion of control" refers to granting the framework control over the implementations of dependencies that are used by application objects [5] rather than to the original meaning of granting the framework control flow (control over the time of execution of application code, e.g. callbacks).