Database – What is Database Management System & Their Components



  • Relationship between two sets of entities A and B is many-to-many when

o For each entity in A, there can be many related entities in the B, and

o For each entity in B, there can be many related entities in A.

  • For example, many students can read many subjects

TABLES:

  • A table consists of rows and columns.
  • Within a table, data is stored as records.
  • A database may contain one or more tables.
  • Each row in a table represents one record.
  • Column is called “Field” and row is called “Record” in database.

QUIRES:

  • Query is the request to extract data from database.
  • It consists of a command that is given to display data.
  • The results of a query are in the form of a table.
  • Main Advantages of using queries are
  1.  o   Extract particular records from one or more tables without modification of the actual data.
  2. o  Sort records in a particular data
  3.  o       Display the selected records on the screen; print them on the printer, etc.

FORMS:

  • Form is a window that collects data from a database and organizes it on the computer screen.
  • It is used to

o Retrieve data from the database and display it. o Enter data into the database.

o  Edit data in the database.

  • Forms are designed to make data entry and retrieval easier.

Advantages:

  • Forms provide a user friendly interface. So non-technical user can work easily.
  • A form usually displays only one record at a time so it is easier to edit and enter data by using form.
  • A form can collect and display data from more than one table.

REPORTS:

  • Presentation of selected data retrieved from a database in a predefined manner is called a Report.

Presentation of data in formatted form.

or

Presentation of processed data obtained from a database is called Report.

  • Report can be displayed on the screen, printed on the paper or stored on the disk.
  • It can retrieve data from one or more tables of a database.

DIFFERENCE BETWEEN FORMS & REPORTS:

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