There are three basic classifications of patterns Creational, Structural, and Behavioral patterns. Creational Patterns • Abstract Factory :- Creates an instance of several families of classes • Builder : - Separates object construction from its representation • Factory Method :- Creates an instance of several derived classes • Prototype :- A fully initialized instance to be copied or cloned • Singleton :- A class in which only a single instance can exist Note : - The best way to remember Creational pattern is by remembering ABFPS (Abraham Became First President of States). Structural Patterns • Adapter :-Match interfaces of different classes . • Bridge :-Separates an object’s abstraction from its implementation. • Composite :-A tree structure of simple and composite objects. • Decorator :-Add responsibilities to objects dynamically. • Façade :-A single class that represents an entire subsystem. • Flyweight :-A fine-grained instance used for efficient sharing...
Relational databases like SQL Server use indexes to find data quickly when a query is processed. Creating and removing indexes from a database schema will rarely result in changes to an application's code; indexes operate 'behind the scenes' in support of the database engine. However, creating the proper index can drastically increase the performance of an application. The SQL Server engine uses an index in much the same way a reader uses a book index. For example, one way to find all references to INSERT statements in a SQL book would be to begin on page one and scan each page of the book. We could mark each time we find the word INSERT until we reach the end of the book. This approach is pretty time consuming and laborious. Alternately, we can also use the index in the back of the book to find a page number for each occurrence of the INSERT statements. This approach produces the same results as above, but with tremendous savings in time. When a SQL Server has ...
An Object-Oriented Database Management System (OODBMS), sometimes referred as Object Database Management System (ODMS) is a Database Management System (DBMS) that supports modeling and creation of data as objects. OODBMS provides support for object classes, class property and method inheritance by sub classes and their objects. A Relational Database Management System (RDBMS) is also a DBMS but, that is based on the relational model. Most popular DBMSs currently in use are RDMSs. As mentioned earlier RDBMS is based on the relational model and data in a RDMS are stored in the form of related tables. So, a relational database can simply be seen as a collection of one or more relations or tables with columns and rows. Each column corresponds to an attribute of the relation and each row corresponds to a record that consists of data values for an entity. RDMSs are developed by extending hierarchical and the network models, which were two previous database systems. Main elements of a RD...
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