What Are Databases? An Overview
What Is A Database?
Databases store information called data in tables. The columns of the tables hold rows of data. Columns may be called "name", "account number" or "dollar amount". Rows contain information such as the name, account number and total amount spent by a customer on a single transaction.
Programs or stored procedures access the information, manipulate it or use it to perform calculations. Indexes help increase the speed of data retrieval. A database view is a designed presentation of the data in the database. Functions are tasks that can be performed on one or many database rows. Database queries are searches of the information within the database.
Types of Databases
Databases are either transactional or analytical. Transactional databases are used to record transactions such as financial transactions during the buying and selling of items. Analytical databases hold volumes of data and perform complex data analysis, such as analyzing many pieces of weather data to create a weather map or reviewing elevation data to create a geographic information system map showing the locations of all pipes and their depths within a given area.
Database designs are object oriented, relational or a hybrid of the two. Relational databases are based on relations between other rows and columns in the database. An item database listing the items available in an online video game containing a list of their attributes along with instructions on how to get them is a common type of relational database.
The combinations of information such as someone's name, address and account number create a tuple or collection of attributes across the database that represent a single entity or person. The relationship between database tables and database objects are called the schema.
Object oriented databases use objects for data presentation and data management. Object oriented databases are intended to create a data representation such as a single individual, holding more information than can be held within a tuple.
Objects in an object oriented database can hold attribute information such as a person's pictures or preferences, more than simply a height, weight and other numeric information. A hybrid between these two models is called an object-relational database management system.
Database schemas determine how the data is structured or organized.
In relational databases, data is organized into tables. XML organizes data into a hierarchy. Object oriented databases store the data in a series of objects. The graph schema allows the data to be linked to other data items in a structure similar to a spider web. Graph schemas are used with object oriented databases.
SQL, the abbreviation for Structured Query Language, is a relational database language developed by IBM and can be found on MySQL database servers. Object oriented databases are generally written in object oriented programming languages. These include but are not to Java and C++.
Query Management Facility or QMF is used for data mining on mainframes and report generation. OPAL is an object oriented programming language.
Oracle is one of the most commonly used database software applications. Another one is Microsoft Access. IBM's Informix Dynamic Server is long standing database application. PowerPlay is a data management software using OLAP for data analysis. QueryEdge is a business intelligence / query tool.
Open DataBase Connectivity or ODBC is an application programming interface that links software applications to an SQL database. Java DB is an open-source relational database offered by Apache. Other database applications exist, as well as middleware software applications to link databases to other software tools, perform data analysis, generate reports to link databases to web pages.
The Job of Database Administrators
Database administrators or DBAs have the authority to create new databases, copy databases or modify the structure of existing databases. Database administrators apply security controls on a database, such as limiting the ability to edit data or copy the entire database. The DBA may have the job of auditing user access logs for potential security violations.
Database managers generally do not enter data into the database; this is done by users. Data managers may have the responsibility of ensuring data quality, training new database users and submitting requests for new database user set ups to the database administrator.
A DBMS is a database management system. An ODBMS is an object oriented database management system. Database Manipulation Language or DML is used in SQL to modify data within a database. Unique identifiers are a unique identification number or code assigned to each database record.
Metadata refers to the information that describes a database record. In a drawing database, the metadata includes the drawing number, drawing revision letter, the drafter and owning project. The metadata record is linked to the database record but is separate from the drawing file itself.
CRM databases or customer relationship management databases store information on potential customers and current customers. CRM databases can also hold attempts by sales people to contact clients, sales figures for different personnel and customer surveys. OLAP stands for OnLine Analytical Processing.