MY_ASSIGNMNT

Data Type- is a kind of data, that is, a set of possible values and basic operations on those values. This contains articles and subcategories about data types generally and about specific, commonly-used data types.
A) What are they and what role do they play in a database?
*Abstract data type (ADT) is a mathematical model for a certain class of data structures that have similar behavior; or for certain data type of one or more programming languages that have similar semantics. An ADT is defined indirectly, only by the operations that may be performed on it and by mathematical constraints on the effects (and possibly cost) of those operations .
For example, an abstract stack data structure could be defined by two operations: push, that inserts some data item into the structure, and pop, that extracts an item from it; with the constraint that each pop always returns the most recently pushed item that has not been popped yet. When analyzing the efficiency of algorithms that use stacks, one may also specify that both operations take the same time no matter how many items have been pushed into the stack, and that the stack uses a constant amount of storage for each element. ADTs are purely theoretical entities, used (among other things) to simplify the description of abstract algorithms, to classify and evaluate data structures, and to formally describe the type systems of programming languages. However, an ADT may be implemented by specific data types or data structures, in many ways and in many programming languages; or described in a formal specification language. ADTs are often implemented as modules: the module's interface declares procedures that correspond to the ADT operations, sometimes with comments that describe the constraints. This information hiding strategy allows the implementation of the module to be changed without disturbing the client programs. Abstract data types are also an important conceptual tool in object-oriented programming and design by contract methodologies for software development.

*Algebraic Data Type (sometimes also called a variant type) is a datatype each of whose values is data from other datatypes wrapped in one of the constructors of the datatype. Any wrapped datum is an argument to the constructor. In contrast to other datatypes, the constructor is not executed and the only way to operate on the data is to unwrap the constructor using pattern matching.

The most common algebraic data type is a list with two constructors: Nil or [] for an empty list, and Cons (an abbreviation of constructor), ::, or : for the combination of a new element with a shorter list (for example (Cons 1 '(2 3 4)) or 1:[2,3,4]).

Special cases of algebraic types are product types , records (only one constructor), sum types or tagged unions (many constructors with a single argument) and enumerated types (many constructors with no arguments). Algebraic types are one kind of composite type (i.e. a type formed by combining other types).

An algebraic data type may also be an abstract data type (ADT) if it is exported from a module without its constructors. Values of such a type can only be manipulated using functions defined in the same module as the type itself.

*Composite Data Types are data types which can be constructed in a program using its programming language's primitive data types and other composite types. The act of constructing a composite type is known as composition.It is constructed from primitive and composite types, and can serve as types themselves when constructing composite types.

*Primitive Data Type can refer to either of the following concepts.It is

* a basic type is a data type provided by a programming language as a basic building block. Most languages allow more complicated composite types to be recursively constructed starting from basic types.
* a built-in type is a data type for which the programming language provides built-in support.

* Recursive Data Type (also known as a recursively-defined, inductively-defined or inductive data type) is a data type for values that may contain other values of the same type. Data of recursive types are usually viewed as directed graphs.Sometimes the term "inductive data type" is used for algebraic data types which are not necessarily recursive.

* Boolean or Logical Data Type is a primitive data type having one of two values: true or false, intended to represent the truth values of logic and Boolean algebra.In programming languages that have a built-in Boolean data type, such as Pascal and Java, the comparison operators such as '>' and '≠' are usually defined to return a Boolean value. Also, conditional and iterative commands may be defined to test Boolean-valued expressions.

Languages without an explicit Boolean data type, like C and Lisp, may still represent truth values it by some other data type. Lisp uses an empty list for false, and any other value for true. C uses an integer type, with false represented as the zero value, and true as any non-zero value (such as 1 or -1). Indeed, a Boolean variable may be regarded (and be implemented) as a numerical variable with a single binary digit (bit), which can store only two values.

*Ordinal Data Type is a data type with the property that its values can be counted. That is, the values can be put in a one-to-one correspondence with the positive integers. For example, strings are ordinal because we can call 'A' the first character, 'B' the second, etc. The term is often used in programming for variables that can take one of a finite (often small) number of values. While the values are often implemented as integers (or similar types such as bytes) they are assigned literal names and the programming language (and the compiler for that language) can enforce that variables only be assigned those literals.

*Real Data Type is a data type used in a computer program to represent an approximation of a real number. Because the real numbers are not countable, computers cannot represent them exactly using a finite amount of information. Most often, a computer will use a rational approximation to a real number.

B)Innumerate at least three DBMS Software.

A database is an integrated collection of logically related records or files that is stored in a computer system.. It consolidates records previously stored in separate files into a common pool of data records that provides data for many applications. The structure is achieved by organizing the data according to a database model. The model that is most commonly used today is the relational model. Other models such as the hierarchical model and the network model use a more explicit representation of relationships.

1)Microsoft Office Access, previously known as Microsoft Access, is a relational database management system from Microsoft that combines the relational Microsoft Jet Database Engine with a graphical user interface and software development tools. It is a member of the Microsoft Office suite of applications and is included in the Professional and higher versions for Windows and also sold separately. There is no version for MacOS or for Microsoft Office Mobile. Access stores data in its own format based on the Access Jet Database Engine. It can also import or link directly to data stored in other Access databases, Excel, SharePoint lists, text, XML, Outlook, HTML, dBase, Paradox, Lotus 1-2-3, or any ODBC-compliant data container including Microsoft SQL Server, Oracle, MySQL and PostgreSQL. Software developers and data architects can use it to develop application software and non-programmer "power users" can use it to build simple applications. It supports some object-oriented techniques but falls short of being a fully object-oriented development tool.

2)CSQL is an open source main memory high-performance relational database management system developed in sourceforge.net. It is designed to provide high performance on simple SQL queries and DML statements.This is mainly developed to be used as a cache for existing disk based commercial databases. Main Memory databases performs 10-20 times faster than the commercial database systems, as it completely keeps the database in main memory.

3)Visual FoxPro is a data-centric object-oriented and procedural programming language produced by Microsoft. It is derived from FoxPro (originally known as FoxBASE) which was developed by Fox Software beginning in 1984. Fox Technologies merged with Microsoft in 1992, after which the software acquired further features and the prefix "Visual". The last version of FoxPro (2.6) worked under Mac OS, DOS, Windows, and Unix: Visual FoxPro 3.0, the first "Visual" version, dropped the platform support to only Mac and Windows, and later versions were Windows-only. The current version of Visual FoxPro is COM-based and Microsoft has stated that they do not intend to create a Microsoft .NET version.

FoxPro originated as a member of the class of languages commonly referred to as "xBase" languages, which have syntax based on the dBase programming language. Other members of the xBase language family include Clipper and Recital. (A history of the early years of xBase can be found in the dBase entry.)

Visual FoxPro, commonly abbreviated as VFP, is tightly integrated with its own relational database engine, which extends FoxPro's xBase capabilities to support SQL query and data manipulation. Unlike most database management systems, Visual FoxPro is a full-featured, dynamic programming language that does not require the use of an additional general-purpose programming environment. It can be used to write not just traditional "fat client" applications, but also middleware and web applications.