10th Class | Unit -3 | Database Management System SAT
Q:- What is Database ? What is its significance ?
Ans:- A database is a collection of logically related data.
The database systems store data centrally at one place wherefrom all applications can get the data required. The centralized storage facilitates many advantages like :
- Controlled redundancy
- Data sharing
- Data consistency
- Standardization
- Enhanced data security
Q:- Write a short note on OOo Base functioning.
Ans:- BASE is a database management system part of OpenOffice.org. it offers many features to manage databases. With BASE, one can manage all information stored in a .odb file.
Q:- What do you understand by tables in a database management system ?
Ans:- In a database management system, various types of objects together manage and maintain the system. Tables are one of them.
A table is a storage container that stores data pertaining to single object, subject or purpose. For example, an employee table may contain all information pertaining to an employee e.g., employee no, employee name, designation, department, grade etc.
Q:- What is the difference between a flat database and relational database ?
Ans:- In a flat database, all the data is stored in a single file e.g. a spreadsheet.
In a relational database, data is stored in multiple tables linked via common fields e.g., BASE of OpenOffice.org is a relational database.
Q:- What is primary Key in a Database ?
Ans:- Primary Key is a designated field in a table, which has a unique value for each record and thus it can uniquely identify every record in the table.
10th Class | Unit -3 | Database Management System SAT
Q:- Explain any three data types in OpenOffice Base?
Ans:- In BASE, we can have following types of Numeric fields :
- Tiny Integer[TINYINT] – This field accepts integers or whole numbers with a fixed length of three spaces.
- Small integer [SMALLINT] – this field accepts integers or whole numbers with a fixed length of five spaces.
- Integer[INT] – this field accepts integers or whole numbers with a fixed length of ten spaces. It is also has an auto value feature that fills up the field with a value you set automatically.
Q:- What do you understand by default value ?
Ans:- The default value is used to specify the default value for a field or control.
The default value is automatically entered in a field or control when a new record is created. For example, in Student table, you might set the default value for House as “Tagore House”. When user add records to the table, they can either accept this value or enter the name of a different house.
Q:- what is the significance of Null values ?
ANs:- Null values are very useful while entering data in a field when table demands data for the field but user does not have any value to enter. Since null values are legal empty values in BASE, they can be entered in such situations.
Q:- What is sorting? How is it useful ?
Ans:- Sorting is a process of arranging the data into some meaningful order on the basis of one or multiple field-values. Sorting makes it easier to understand, analyse or visualize data.
Q:- What is relationship in a database ? how are relationship between tables useful?
Ans:- in a relationship database, a relationship is a link that connects two or more tables through some common, related data.
Relationship between tables enable users to use the related data across multiple tables.
10th Class | Unit -3 | Database Management System SAT
Q;- Name the three types of relationships that can be created in Base.
Ans:- There are 3 types of relationship in relational database :
- One-to-One
- One-to-Many
- Many-to-Many
Q:- Explain One-to-one Relationship.
Ans:- in a one-to-one relationship, a record in a table A can have only one matching record in Table B. and vice versa. For example, a person has 1:1 relationship with his spouse.
Q:- Explain one-to-many relationship. Is it different from many-to-one relationship ?
Ans:- In one-to-many relationship a record in table A can have many matching records in table B, but a record in table B can have only one matching record in table A.
One-to-many and Many-to-One relationships are two sides of the same coin e.g. in the above diagram Teacher and Student tablet have one-to-many relationship while student and teacher tablets have many-to-one relationship.
Q:- Give some examples of one-to-one relationships.
Ans:- Some examples of one-to-one relationships are :
- A Student ID for a school is connected to a single student.
- A driver generally has one license.
- An edition of a book has one publisher.
- A country has one capital.
Q:- Give some examples of one-to-many relationships
Ans:- some examples of one-to-many relationships are :
- A car(one) and its parts (many)
- A woman (one) and her children (many)
- A large company(one) and its offices (many)
- A zoo (one) and its animals
Q:- What is referential integrity ?
Ans:- Referential integrity is a system of rules that a DBMS uses to ensure that the relationships between records in related tablets are valid and that users don’t accidentally delete or change related data.
Q:- What is Query ?
Ans:- A query is a way to get specific information from the database.
Q:- What is the utility of queries in a database ?
Ans:- A query is a useful way to extract required data from a database. It offers many advantages :
- Queries show only the required data.
- Queries represent required data in a presentable way.
- Queries can be saved for later use also.
Q:- What are two ways of creating queries in Base ?
Ans:- In Base queries can be created :
- Through query wizard
- Through Query Design View
Q:- What is the role of Criterion in a Query ?
Ans:- The Criterion in a query specifies the condition in a detailed query in which all records that fulfil the condition specified in Criterion.
Q:- How is a detailed query different from a summary query ?
ANs:- In a detailed query all records that match the specified criterion are displayed. In a summary query only the aggregated/grouped result such as the sum, average, minimum or maximum value is shown.
Q:- What is SQL ? What are different categories of commands available in SQL?
Ans:- In order to access data within the ORACLE database, all programs and users must use, structured query language. SQL is the set of commands that is recognized by nearly all RDBMSs. SQL commands can be divided into following categories :
- Data Definition Language (DDL) Commands.
- Data Manipulation Language (DML) commands.
- Transaction Control Language(TCL) commands.
- Session control commands.
- System control commands.
Q:- Differentiate between DDL and DML commands.
Ans:- The Data Definition Language (DDL) commands, as the name suggests, allow you to perform tasks related to data definition. That is , through these commands, you can perform tasks like, create, alter and drop schema objects, grant and revoke privileges etc.
The Data Manipulation Language (DML) commands, as the name suggests, are used to manipulate data. That is, DML commands query and manipulate data in existing schema objects.
Q:- Differentiate between CHAR and VARCHAR datatypes.
Ans:- The difference between CHAR and VARCHAR is that of fixed length and variable length. The CHAR datatype specifies a fixed length character string. When a column is given datatype as CHAR(n), then MYSql ensures that all values stored in that column have this length i.e. n bytes. If a value is shorter than this length n then blanks are added, but the size of value remains n bytes.
VARCHAR, on the other hand, specifies a variable length string. When a column is given datatype as VARCHAR(n), then the maximum size a value in this column can have is n bytes. Each value that is stored in this column stores exactly as we specify it i.e. no blanks are added if the length is shorter than maximum length n.
Q:- What is a Form? What is its utility ?
Ans:- A form is an interactive screen that contains numerous fields, or spaces to enter data. Each field holds a field label and data box which shows data corresponding that field, coming from the linked/query.
A form is a user friendly way to access and insert data into fields of a table or a query.