database management

As there are 2 types of data independence i.e physical data independence and logical data independence and any changes made at the lower level would be absorbed by mapping between 2 levels. However in order to obtain physical data independence that requires the conceptual level not to specify...

There are various components that are used in DBMS: Query Processor: Transforms user queries to series of low level instructions. Runtime Database Manager: It is also known as Database central system. It is the central software components that accepts queries from user, process it and return it...

The Object Management Group is a committee of international industry. That is made for promoting the theory an practice of object oriented software development. The goal of the committee is developed a common architectural framework , which support the any type of hardware and software...

After database structure is defined, it gets ready for updation and manipulation. Data manipulation language, performs the tasks with the commands to enable users to edit, delete or update the data. With these details users can add new records tothe database, update the records, delete the...

Data Definition Language is used to define the structure of a database. DDL includes the below mentioned factors : 1. Definition of data elements included in database. 2. Organization of data elements into respective records. 3. Definition of field name, length, type and data element. 4...

Data dictionary is a tool which helps in recording and processing of information about the data that any organization uses. Data dictionary can be used as repository for common code. Data dictionary is a also termed as central catalogue for metadata. It can be integrated within the database...

In Relational DBMS relation between two tables or files can be specified at the same time or whiel table creation. Most of the RDBMS supports client and server architecture. RDBMS support distributed database. Many tables are grouped in one data base in relational database management system.One...

Normalization is a process which helps in the collection of data in a single table is replaced, by the same data being distributed over multiple tables with a specific relationship being setup between the tables. This is a process that helps analysts or database designers to design table...

The benefit of database management system are as mentioned below : The amount of data redundancy in stored data can be reduce. No more data in database management is in consistencies. Stored data can be shared by a single or multiple users using database management system. Security of data can...

The main advantage of using database system is that the organization can expend and control over the data. The database administrator is the control over the data and change it structure of a data requires and arrangement. Apart from this these are the advantages of database which are described...

The VSAM is the virtual storage access method, which is the IBM’s advanced version of index sequential file organization that avoids the disadvantages of index sequential file organization. The VSAM is the made with the two components that is the index and the data. The VSAM Index and the data...

Subqueries A subquery is defined as SELECT query. Subquery returns the single data or multiple data. Subqueries may be nested within the SELECT, INSERT, UPDATE and DELETE commands. We use the subqueries for retrieving data from the single table or multiple tables. Subqueries are used inside...

It is Object Oriented distributed database system. It support the client server architecture. The server of the database responsible for the reading and writing the data permanently in the storage. Server also responsible for the managing the concurrent access the data from multiple client. The...

There are number of factors that may become the barrier to Distributed DBMS. The basic failure or barrier to the Distributed DBMS are listed as mentioned below : 1.Site failure. 2.Loss or message or corrupt message. 3. Communication barrier. 4.Network disconnection or partition. The system...

Data servers are basically used in local area networks with a high speed internet connection between the client and server machine.ln data server management, client server are addressed on terms of processing power to the server machine and this architecture is totally based on full back-end...

Non-two phase locking protocol is used to prevent deadlock. In non-two phase locking protocol it requires prior knowledge about the order in which the transection is to be executed. It includes: Graph based protocol: It requires that we must have prior knowledge about the order in which the...

Joins are basically used to combile two or more tables i.e in order to retrieve the data stored in 2 different table we need to join those tables in a query. There are various types of joins: Theta or Equi join: In this condition to join 2 or more tables are specified by = operator. Eg: Select...

A relation is said to be in third NF if and only if, it is in second NF and no non-key attribute is transitively dependent on primary key whereas, a relation is said to be in BCNF if and only if every determinant is a candidate key. Third normal form is weaker than BCNF whereas BCNF is stronger...

Data dictionary is basically used to provide the knowledge about the data that is to be stored into the database. It includes: Name Datatype Range Access authorization Source Data dictionary is also used by the programmer to develop the programs, queries, managing and manipulating data. It is...

The various functions performed by File manager are: It is responsible for maintaining files and its structure. It takes the query from the data manager, locates the block containing the requested record, then it interact with the disk manager requesting for the block. Once the block is...