DBMS (Database Management System)

By Notes Vandar

Data and information

Data: Data are the raw facts and figure with are isolated and uninterpreted generally represented by letter and numbers. Data undergoes processing. Eg, 32, John, 12

Information: The collection of meaningful results obtained after processing raw data. They are generated after processing. Eg. John is 32 years old and he reads in class 12.

Database: The systematic and scientific collection of data that can access quickly whenever required is called a database. It is an organized way of collecting and keeping data and information. E.g. Dictionary, telephone directory, marks ledger, attendance register.

DBMS and its advantages

DBMS: DBMS stands for Database Management System which is the collection of software that is used to manage databases i.e. storing, manipulating, and retrieving data systematically and scientifically. It is software used to store, process, and access data and information whenever required. Eg, MS-Access, MY SQL, Oracle, dBase, Foxpro

Advantages of DBMS.

  1. It helps in faster access to data.
  2. It helps to reduce the duplication of data.
  3. It helps to provide security and privacy to data.
  4. It helps in data sharing.
  5. Easy to modify the data

Q) Differentiate between database and DBMS with examples. [V.imp]

Database DBMS
It is a collection of related data. It is software to maintain the database.
It is not secured. It is highly secured.
Data sharing is impossible. Data can be easily shared in a network
Every DBMS has a database. Every database doesn’t have DBMS.
Eg, Dictionary, telephone directory Eg, MY SQL, Oracle.

MS-Access: It is a DBMS developed by Microsoft corporation for organizing data in the form of tables. It allows users to add, edit, delete, sort, modify, share, and print records. Feature of MS-Access.

  1. Easy to store data and information.
  2. Easy to enter, edit, delete and display data.

Objects / Elements of DBMS

A) Table: The primary building block of DBMS where data are organized in tabular form i.e rows and columns. The columns of a database table are called fields whereas, rows are called records. Importance of table.

  1. Helps to store data in an organized group.
  2. Easy to sort distinct records.
  3. Fields of the table help to store different types of data on different topics.

B) Form: The element/object of the database which allows the user to enter new data and edit the existing one easily through a user-friendly interface. Importance of form.

  1. It provides a user interface through which users can enter data.
  2. It helps to modify records.

C) Query: The important object of the database which is used to retrieve/access and interpret the information according to the user’s requirement. Importance of query.

  1. It helps in faster access to data.
  2. It helps to display information as per the user’s condition.
  3. It helps in sorting and filtering data.

Types of Query

  1. Select query: Used to retrieve data from one or more tables depending upon the condition.
  2. Action Query: Used to make changes to records available in the database. Types are
    1. Update query: Used to make global (All at once) changes to several records in different tables.
    2. Append query: Used to add more records in existing one or more tables.
    3. Delete query: Used to delete one or more records from one or more tables.
    4. Make-table query: Create a new table link to one or more available tables in the database.

D) Report The object of the database which is used to generate results after processing data in a database. It is an effective way of displaying data either in soft copy (monitor) format or hard copy (printed) format. Important of the report.

  1. It helps to generate a summary after processing data.
  2. It can be used to generate invoices, bills, statements,s and labels.
  3. It helps to generate results in attractive and effective ways.

Data types: The characteristics of a field that specifies what kind of data can be stored in the given field are called data types. The following are the data types used in MS Access.

S.N Data Type Purpose/use Size
1. Text Alphanumeric characters 0-255 characters / 256 characters
2. Memo Alphanumeric characters 0-65,535 characters / 65,536 characters
3. Number Numeric Values Integer (2 bytes) Long integer (4 bytes)
4. Date/Time Date and time data 8 bytes
5. Currency Currency data 8 bytes
6. Auto-number A sequential unique serial number automatically increased by 1 4 bytes
7. Yes/No Logical Values 1 bit
8. OLE object (Object Link Embedded) Pictures, audio, video, graphics, documents 1GB
9. Hyperlink Link with several applications and websites 2048 characters
10. Look, Wizard Create a field that allows selecting a value. 4 bytes

Field properties

  1. Field size: It is used to set the maximum size for the data stored in a given field. For eg, the maximum number of characters (size) stored in the text field is 256 characters. The default field size is 50.
  2. Format: It is used to display formatted output which means data can be displayed in different formats and layouts. For eg, < (Display content in lower case), > (Display content in upper case).
  3. Input mask: It is used to specify the format in which data can be entered.
  4. Caption: It is used to display an alternate name for the field to make it more descriptive. It can contain 2048 characters.
  5. Default value: It is the value or information that is displayed automatically when we add a new record in the table for a field.
  6. Validation rule: It enables the user to limit values that can be accepted by a particular field. It can contain 2048 characters.
  7. Validation text: The message that is displayed when the validation rule is violated or not followed.
  8. Required: It is used to specify whether the data must be entered or not in the particular field.
  9. Indexed: It is used to speed up the searching and sorting of records from the database table.

Some important terms used in DBMS

1) Extension of MS-Access database file is. MDB

2) Primary key(v.imp): The key or field that is used to uniquely identify records from the database table is called the primary key. It must be unique and cannot be kept empty(null). Importance of primary key.

  1. It uniquely identifies records.
  2. It helps in faster access to data.
  3. It helps to prevent duplication of data.
  4. It avoids empty(null) values.
  5. It is used to establish table relationships.

3) Table relationship: The logical link between two or more two tables of a database using unique key fields is called a table relationship. Types are one-to-one, one-to-many, many to many.

Types of Database Relationship

Types of Database Relationships


4) Sorting: Arranging data in a particular order of field i.e. ascending or descending is called sorting. Helps in faster access to data.

5) Filtering: The process of making a selection of records depending on the supplied criteria is called filtering. Helps in faster access to data.

6) DBA: DBA stands for Database Administrator a person or specialist who is responsible to manages and monitoring overall resources and operations (such as analyzing, planning, operating, implementing, and securing) associated with DBMS. Responsibilities of DBMS.

  1. Planning database activities.
  2. Securing database and system.
  3. Implementing modern tools and technology.
  4. Maintaining database.
  5. Providing user safety and privacy.
Important Questions
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