by Dinesh Thakur Category: DBMS & RDBMS

A DBMS must provide appropriate languages and interfaces for each category of users to express database queries and updates. Database Languages are used to create and maintain database on computer. There are large numbers of database languages like Oracle, MySQL, MS Access, dBase, FoxPro etc. SQL statements commonly used in Oracle and MS Access can be categorized as data definition language (DDL), data control language (DCL) and data manipulation language (DML).



 
by Dinesh Thakur Category: DBMS & RDBMS

A metadata (also called the data dictionary) is the data about the data. It is the self describing nature of the database that provides program-data independence. It is also called as the System Catalog. It holds the following information about each data element in the databases.



 
by Dinesh Thakur Category: DBMS & RDBMS

Functions of Data Base Administrator

Data Base Administrator (DBA) is a person or group in charge for implementing DBMS in an organization. Database Administrator's job requires a high degree of technical expertise and the ability to understand and interpret management requirements ata senior level. In practice the DBA may consist of team of people rather than just one person



 
by Dinesh Thakur Category: DBMS & RDBMS

Any access to the stored data is done by the data manager. A user's request for data is-received by the data manager, which detern1ines the physical record required. The decision as 10 which physical record is needed may require some preliminary consultation of the database and/or the data dictionary prior to the access of the actual data itself.



 
by Dinesh Thakur Category: DBMS & RDBMS

A major objective for three-level architecture is to provide data independence, which means that upper levels are unaffected by changes in lower levels.

There are two kinds of data independence:

 
by Dinesh Thakur Category: DBMS & RDBMS

Database changes over time when information is inserted or deleted. The collection of information stored in the database at a particular moment is called an instance of the database. The overall design of the database is called the database schema.



 
by Dinesh Thakur Category: DBMS & RDBMS

DBMS A database management system is the software system that allows users to define, create and maintain a database and provides controlled access to the data.

A Database Management System (DBMS) is basically a collection of programs that enables users to store, modify, and extract information from a database as per the requirements. DBMS is an intermediate layer between programs and the data. Programs access the DBMS, which then accesses the data. There are different types of DBMS ranging from small systems that run on personal computers to huge systems that run on mainframes. The following are main examples of database applications:



 
by Dinesh Thakur Category: DBMS & RDBMS

In order to remove all limitations of the File Based Approach, a new approach was required that must be more effective known as Database approach

The Database is a shared collection of logically related data, designed to meet the information needs of an organization. A database is a computer based record keeping system whose over all purpose is to record and maintains information. The database is a single, large repository of data, which can be used simultaneously by many departments and users. Instead of disconnected files with redundant data, all data items are integrated with a minimum amount of duplication.



 
by Dinesh Thakur Category: DBMS & RDBMS

File processing systems was an early attempt to computerize the manual filing system that we are all familiar with. A file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. File systems may use a storage device such as a hard disk or CD-ROM and involve maintaining the physical location of the files.



 
by Dinesh Thakur Category: DBMS & RDBMS

Hierarchical Database Model

Hierarchical Database model is one of the oldest database models, dating from late 1950s. One of the first hierarchical databases Information Management System (IMS) was developed jointly by North American Rockwell Company and IBM. This model is like a structure of a tree with the records forming the nodes and fields forming the branches of the tree.



 
by Dinesh Thakur Category: DBMS & RDBMS

The Database Users fall into several categories:


Application Programmers are computer professionals interacting with the system through DML calls embedded in a program written in a host language (e.g. C, PL/1, Pascal): These programs are called Application Programs. The DML Precompiled converts DML calls (prefaced by a special character like $, #, etc.) to normal procedure calls in a host language.



 
by Dinesh Thakur Category: DBMS & RDBMS

Database System Structure are partitioned into modules for different functions. Some functions (e.g. file systems) may be provided by the operating system. Components include:



 
by Dinesh Thakur Category: DBMS & RDBMS

There are four basic components of Database Management System:

(i) Data: Raw facts which we want to feed in the computer.

(ii) Hardware: On which the data to be processed.

(iii) Software: The interface between the hardware and user, by which the data   will change into the information.

(iv) User: There are so many types of users some of them are application programmer, end case users and DBA.



 
by Dinesh Thakur Category: DBMS & RDBMS

A Database Administrator, Database Analyst or Database Developer is the person responsible for managing the information within an organization. As most companies continue to experience inevitable growth of their databases, these positions are probably the most solid within the IT industry.



 
by Dinesh Thakur Category: DBMS & RDBMS

SQL statements are divided into two major categories: data definition language (DDL) and data manipulation language (DML).

Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:



 
by Dinesh Thakur Category: DBMS & RDBMS

When multiple transactions are trying to access the same sharable resource, there could arise many problems if the access control is not done properly. There are some important mechanisms to which access control can be maintained. Earlier we talked about theoretical concepts like serializability, but the practical concept of this can be implemented by using Locks and Timestamps.

 
by Dinesh Thakur Category: DBMS & RDBMS

What is a database server? It is similar to data warehouse where the website store or maintain their data and information. A Database Server is a computer in a LAN that is dedicated to database storage and retrieval. The database server holds the Database Management System (DBMS) and the databases. Upon requests from the client machines, it searches the database for selected records and passes them back over the network.



 
by Dinesh Thakur Category: DBMS & RDBMS

What is a Database View, A view can join information from several tables together, or we can say that Views are useful for Hiding unwanted information for example adding the ename field to the Order information. Database View is a subset of the database sorted and displayed in a particular way. A database view displays one or more database records on the same page. A view can display some or all of the database fields.



 
by Dinesh Thakur Category: DBMS & RDBMS

The environment of database is said to be instance. A database instance or an ‘instance’ is made up of the background processes needed by the database software. These processes usually include a process monitor, session monitor, lock monitor, etc.  They will vary from database vendor to database vendor.



 
by Dinesh Thakur Category: DBMS & RDBMS

A database object in a relational database is a data structure used to either store or reference data. The most common object that most people interact with is the table. Other objects are indexes, stored procedures, sequences, views and many more.



 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.