5SA

Describe the elements in a database

: A database is a self-describing collection of integrated records that is organized based on a hierarchy of data elements. A byte is a character of data. Bytes are grouped into columns. Columns are also called fields. A key is a column or group of columns that identifies a unique row in a table. Columns that are keys of a different table than the one in which they reside are called foreign keys. Columns or fields, in turn, are grouped into rows, which are also called records. Finally, a group of similar rows or records is called a table or a file. A database contains, within itself, a description of its contents called metadata. Metadata are data that describe data. Thus, a database is a collection of tables plus relationships among the rows in those tables, plus special data, called metadata, that describes the structure of the database.

What is a database application?

A database application is a collection of forms, reports, queries, and application programs that serves as an intermediary between users and database data. Database applications reformat database table data to make it more informative and more easily updated. Application programs also have features that provide security, maintain data consistency, and handle special cases. The specific purposes of the four elements of a database application are: Forms - View data; insert new, update existing, and delete existing data. Reports - Structured presentation of data using sorting, grouping, filtering, and other operations. Queries - Search based upon data values provided by the user. Application programs - Provide security, data consistency, and special-purpose processing, e.g., handle out-of-stock situations.

Describe the merits of metadata.

A database is self-describing in that it contains, within itself, a description of its contents. This is because it contains not only data, but also data about the data in the database. This data is known as metadata. It is the presence of metadata that makes databases much more useful than spreadsheets or data in other lists. Because of metadata, no one needs to guess, remember, or even record what is in a database. To find out what a database contains, we just look at the metadata inside the database.

Describe the functions of a database management system (DBMS).

A database management system (DBMS) is a program used to create, process, and administer a database. 1. Database developers use the DBMS to create tables, relationships, and other structures in the database. To create a new table, the developer just fills out a new table's metadata into a form. To modify an existing table—for example, to add a new column—the developer opens the metadata form for that table and adds a new row of metadata. 2. The second function of the DBMS is to process the database. The DBMS provides applications for four processing operations: to read, insert, modify, or delete data. These operations are requested in application calls upon the DBMS. From a form, when the user enters new or changed data, a computer program that processes the form calls the DBMS to make the necessary database changes. From a Web application, a program on the client or on the server application program calls the DBMS directly to make the change. 3. The third DBMS function is to provide tools to assist in the administration of the database. Database administration involves a wide variety of activities. For example, the DBMS can be used to set up a security system involving user accounts, passwords, permissions, and limits for processing the database. In addition to security, DBMS administrative functions include backing up database data, adding structures to improve the performance of database applications, removing data that are no longer wanted or needed and similar tasks.

What is a database management system (DBMS)? Explain with suitable examples.

A database management system (DBMS) is a program used to create, process, and administer a database. A DBMS is different from a database in that a DBMS is a software program while a database is a collection of tables, relationships, and metadata. Almost no organization develops its own DBMS. Instead, companies license DBMS products from vendors such as IBM, Microsoft, Oracle, and others. Popular DBMS products are DB2 from IBM, Access and SQL Server from Microsoft, and Oracle Database from the Oracle Corporation. Another popular DBMS is MySQL, an open source DBMS product that is license-free for most applications.

What is a NoSQL database management system?

A few years back, Amazon.com determined that relational database technology wouldn't meet its processing needs, and it developed a nonrelational data store called Dynamo. Google (developed Bigtable) and Facebook (developed Cassandra) also followed suit. Such nonrelational DBMS have come to be called NoSQL DBMS. This term refers to software systems that support very high transaction rates processing relatively simple data structures, replicated on many servers in the cloud. The rise of NoSQL does mean that, for large organizational IS, choosing a relational DBMS is no longer automatic. NoSQL DBMS products are very technical and can be used only by those with a deep background in computer science.

Discuss the creation of a database. Explain its working.

Database developers use the database management system (DBMS) to create tables, relationships, and other structures in the database. A form is used to define a new table or to modify an existing one. To create a new table, the developer just fills the new table's metadata into the form. To modify an existing table, a developer opens the metadata form for that table and adds a new row of metadata.

What are relational databases? Discuss their drawbacks that led to the development of nonrelational style of database processing.

Databases that carry their data in the form of tables and that represent relationships using foreign keys are called relational databases. Foreign keys are columns that are keys of a different table than the one in which they reside. The relational model was the single, standard way of processing databases for over thirty years. Recently, however, new styles of database processing have started appearing. Part of the reason is that the major principles of the relational model—fixed-sized tables, representing relationships with foreign keys, and the theory of normalization came about because of limited storage space and limited processing speeds back in the 1960s and early 1970s. At some point, maybe the mid-1990s, these limitations were removed by improved storage and processing technology and today they do not exist. In other words, the relational model is not needed today. Other reasons for the development of nonrelational databases include the need to gain faster performance using many servers and to store new types of data such as images, audio, and videos.

Define Structured Query Language (SQL).

Structured Query Language (SQL) is an international standard language for processing a database. DBMS products like DB2 from IBM, Access and SQL Server from Microsoft, and Oracle Database from the Oracle Corporation accept and process SQL statements. Another popular DBMS that accepts SQL statements is MySQL, an open source DBMS product that is license-free for most applications. One need not understand or remember SQL language syntax. Instead, one needs to just realize that SQL is an international standard for processing a database. Also, SQL can be used to create databases and database structures.

In the context of data storage, explain the difference between a spreadsheet and a database.

The purpose of both a spreadsheet and a database is to keep track of things. However, unlike a spreadsheet, a database offers the solution of being able to keep track of more than one type of data. Lists of data involving a single theme can be stored in a spreadsheet. However, lists that involve multiple themes require a database.