What is null described testing for null in sql?, Database Management System

Assignment Help:

What is NULL? Give an example to described testing for NULL in SQL?

The NULL SQL keyword is used to represent either a missing value or a value which is not applicable in a relational table. Consider there is a relation:

Person(id, name, address, phone)
Now to search ids and names of person who do not have a phone is:
Select id, name
from Person
where phone is null

Related Discussions:- What is null described testing for null in sql?

Data replication, Data Replication "If a relation R has its copies kept...

Data Replication "If a relation R has its copies kept at two or more sites, then it is considered replicated". But why do we replicate a relation? There are several advan

Complete replication-data replication, Complete replication: It implies ma...

Complete replication: It implies maintaining of a whole copy of the database at every site. Thus, the reliability & availability and performance for query response are maximized.

Database application and creation, Create Relational Database Model (RDM) f...

Create Relational Database Model (RDM) for Sailing bed and breakfast club Table_Name( attribute_1, attribute_2, attribute_3, ? ,attribute_x) Primary Key ( attribute_1, attribute_2)

Primary key, The primary key is selected from the

The primary key is selected from the

Money making supermarket chain problem, Consider the ER schema below for th...

Consider the ER schema below for the MoneyMaking supermarket chain problem. Translate the given ER schema into SQL CREATE TABLE statement.

Describe five main functions of a database administrator, Describe five mai...

Describe five main functions of a database administrator. Ans: A database administrator (DBA) is a person who is accountable for the environmental aspects of a database. Genera

Key, Q. Explain the terms key constraints participation constraints and m...

Q. Explain the terms key constraints participation constraints and mapping caradinalities in ER model. Participation Constraints : The participation of an entity set E i

Enhanced entity relationship, what do you understand by enhanced entity-rel...

what do you understand by enhanced entity-relationship

Define deadlock recovery measures, Define Deadlock recovery measures ...

Define Deadlock recovery measures To recover from deadlock, the cycle in the wait-for-graph should be broken. The common technique of doing this is to rollbac

Can a filed occur in several field groups, Can a filed occur in several fie...

Can a filed occur in several field groups. Yes. But it leads to redundant data redundancy.

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages