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A query is an inquiry into the database using the SELECT statement. These statements give you filtered data according to your conditions and specifications indicating the fields, records, and summaries which a user wants to fetch from a database.

A primary key uniquely identifies the record in the table.

A primary key cannot allow null values and must have a unique index.

(a) The main building blocks of database are tables, queries, forms and reports.

A foreign key is used to Establish the relationship between any two tables of RDBMS.

The default extension of OO.o BASE database is .odb.

• Storage of information.

• Retrieval of information quickly.

• Sorting, selecting data that satisfies certain criteria (filtering).

• Produce the report in some standardized and readable format.

RDBMS is a type of DataBase Management System that stores data in the form of relations (tables). Relational databases are powerful, so they require few assumptions about how data is related or how, it will be extracted from the database.

Cartesian Product 

Degree — 4 

Cardinality = 6

A database consists of several components. Each component plays an important role in the database system environment. 

The major components of the database are as follows: 

Data 

It is raw numbers, characters or facts represented by value. Most of the organizations generate, store and process a large amount of data. The data acts as a bridge between the hardware and the software. Data may be of different types such as User data, Metadata and Application Metadata. 

Software 

It is a set of programs that lies between the stored data and the users of the database. It is used to control and manage the overall computerized database. It uses different types of software such as MySQL, Oracle etc. 

Hardware 

It is the physical aspect of the computer, telecommunication, and database, which consists of the secondary storage devices such as magnetic disks, optical discs etc., on which data is stored. 

Users 

It is the person, who needs information from the database to carry out its primary business responsibilities.

The various types of users which can access the database system are as follows: 

Database Administrator (DBA) 

A person, who is responsible for managing or establishing policies for the maintenance and handling of the overall database management system is called DBA. 

Application Programmers 

The people, who write application programs in programming languages to interact and manipulate the database are called application programmers. 

End-user 

A person, who interacts with the database system to perform different operations on the database by inserting, deleting etc., through menus or forms.

(i) DateofBirth 

(ii) Admno 

(iii) Phonenumber

(b) Key is a data item that allows you to uniquely identify individual occurrences which is defined as the column or set of columns.

Database is a collection of related information.

Fields are one type of information. A record contains logically related fields. A table Emp name contains logically related records.

Here EmpNo, Name, and Salary are three different fields. 1, Shridhar, 20000 represents one complete record.

(a) The form enables people to enter or view data in a database easily.

(d) A record refers to a raw of data, which represents a complete set of information in a table.

False If we create multiple primary keys in a table, the primary key will be unable to find the unique key value.

True When a table’s primary key field is added to a related table in order to create the common field which relates two tables, it is called a foreign key in the related table.

Possible primary keys for an Employee table are emp code, emp phone number.

The primary key is used to uniquely identify the record in a database. It can be a column or a set of columns in the table. 

Main features of the primary key are as follows:

1. It must contain a unique value for each record of the table.

2. It does not contain null values.

A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

A foreign key is a reference of the primary key in another table.

The candidate key, which is not used as primary key is called alternate key.

A field which uniquely identifies each record in a table is known as the primary key. e.g. emp id is the primary key of the Employee table.

The candidate key is a column or set of columns that can help in identifying records uniquely. 

Example, consider a Table STUDENT.

Here, AdmnNo & Roll No define Table uniquely. 

Hence, they are candidate keys

A table may have more than one such attribute or a group of an attribute that identifies a row/ tuple uniquely, all such attribute(s) are known as Candidate keys. Out of the Candidate keys, one is selected as Primary key.

Table: Stock

Id = Primary key Id and Qty = Candidates Keys

1. No

2. Degree = 4 

Cardinality = 5 

[Hint: Because Pencil and Eraser are having the same Mno = 2. Primary key needs to be unique]

1. Cardinality = 4 Degree = 5

2. Cardinality = 7

3. Degree = 6

Degree is the number of attributes or columns present in a table. 

Cardinality is the number of tuples or rows present in a table. 

Patients Degree = 4 

Cardinality = 5

A set of related data item is called as record.

AdmissionNo should be set as the primary key because admission numbers are unique for each and every student of the school, which is not possible in the case with RollNo and Name.

1. 95.4

2. Mohan Garg and scholarship awarded is 50000.

3. 5

4. 6

1. EmpNo can be selected as a primary key. 

2. EmpName is having unique values, but there is no guarantee that if more employees are included then there would not be multiple people with similar names. 

So, in future, its values may be duplicate. Thus, it cannot be made as a primary key.

Degree = 4 x 5 = 20 [no. of columns] 

Cardinality = 10 x 5 = 50 [no. of rows]

1. DBMS is used to store data at a centralized location.

2. It is used to minimize data redundancy and data inconsistency.

(b) Date of birth is the most appropriate data field in the context of the employee table.

Male and Female

Field is the smallest part of a table in which one data item can be kept.

Degree = 10 [no. of cols] 

Cardinality = 10-3 = 7 [no. of rows]

(c) Numeric calculator because it is used to calculate the numeric numbers only as it is unable to store data.

(a) Users are those persons, who need the information from the database to perform operations.

A field in a table is also called as column.

A domain is a pool of values from which the actual values appearing in a given column are drawn. 

For example, The values appearing in the Supp# column of both the suppliers' table and the Shipment table are drawn from the same domain.

Shipment

Supplier

Degree = 3 

Cardinality = 30 (20 + 15 – 5)

(d) DBMS is a collection of programs that enable the user to create and maintain the database. Also, it is a computer-based record keeping system.

(a) A database consists of several components. These are data, software, hardware, and user.

The full form of DBMS is a Database Management System. It is a computer based record keeping system.

A field is an area, reserved for a specific piece of data. It is also known as an attribute, e.g. Customer_Name.

1. SQL – Structured Query Language.

2. DBMS – Data Base Management System.

To provide a convenient and efficient environment in which we can store and retrieve information.