class 11 IP Database Concepts notes
1. What is database?
It is a collection of related information.
2. What is Database Management Systems (DBMS)?
It is a software to store and maintain data in the form of tables. We can easily create, modify, delete and view information from database.
Examples: MySQL, SQLite, SQL Server, Oracle etc.
3. Write disadvantages of File Management Systems?
- Redundancy of data.
- Data Inconsistency.
- No security of data.
- Data can’t be shared.
4. Write advantages of Database Management Systems (DBMS)?
- Redundancy of data is reduced.
- Data Inconsistency is removed.
- Security of data can be provided.
- Data can be easily shared.
- Standards can be enforced.
5. Write limitations of Database Management Systems (DBMS)?
- Security may be compromised.
- Integrity may be compromised.
6. What is relational data model?
It is a data model in which information is represented as collection of related tables. Table is also known as relation. Each relation has a unique name.
7. Define a relation.
Relation is also called a table. Relation is defined as a collection of data in the form of rows and columns.
Example:
| Relation: Student | |||
| RegNo | Name | Class | PhoneNo |
| A101 | Manoj | 12 A | 99878989898 |
| B202 | Mohit | 12 B | 8011988880 |
| B303 | Vijay | 12 A | 9008776655 |
8. What is domain?
Domain is set of values that can be put into a particular field of a table.
Example:
i. The domain of Name column is string values.
ii) The domain of PhoneNo is set of integer values.
9. What is attribute?
It is also known as field or column of a table. It is the smallest piece of information.
Example: In above table, RegNo, Name and PhoneNo are attributes.
10. What is tuple?
Tuple is also called record or row. It is defined as collection of attributes. It is used to store information about a single entity.
Example:
In above table, one row gives information about one student only. B303, Rohit, 12A, 9008776655 specifies one row.
11. Define Primary Key?
It is set of one or more columns that can uniquely identify records within a table
Example: In above table student, RegNo can be Primary key as registration number of students is always unique.
12. Define Candidate Key?
Fields of a table that can serve as primary key are called Candidate keys i.e. these fields should contain unique values only.
Example: In above table student, RegNo and PhoneNo can be Candidate key as both these field contain unique values.
13. Define Alternate Key?
Out of the candidate keys, one can can as primary key, the remaining keys are called alternate key.
Example: In above table student, RegNo is primary key and PhoneNo is alternate key
14. Define Foreign Key?
It is a field whose values are derived from primary key of another table. Foreign key can be used to establish a link between two tables.
15. Define Degree?
Number of attributes (columns) in a table is known as degree of that table.
Example: Degree of table student is 4 as it contains 4 fields.
16. Define Cardinality?
Number of tuples (rows) in a table is known as cardinality of that table.
Example: Cardinality of table student is 3 as it contains 3 records.
17. What is SQL?
SQL stands for Structured Query Language. It is a standard language used for accessing database objects. It can be used to create a table, manage manipulate data in it.
SQL can be used to perform following tasks:
- Create, modify and drop tables.
- Inserting, updating, and deleting records in a table
- Display records from a table.
- Controlling access to the database and tables.
- Applying constraints to tables.
18. Explain types of SQL Statements.
The SQL statements are categorized into following categories
i. Data Definition Language (DDL) statement
ii. Data Manipulation Language (DML) statement
iii. Transaction Control Statement
iv. Session Control Statement
v. System Control Statement
19. Explain DDL and DML statements of SQL.
a. DDL stands for Data Definition Language. It is a set for commands used to create, modify and delete structures of database and its objects. There are three DDL statements
- CREATE TABLE
- ALTER TABLE
- DROP TABLE.
b. DML stands for Data Manipulation Language (DML). It is a set of commands to insert, delete, modify and retrieve data from database tables. There are four DML statements:
- SELECT
- UPDATE
- DELETE
- INSERT