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?

What is difference between truncate and delete, What is difference between ...

What is difference between TRUNCATE and DELETE? - Truncate can't be rolled back whereas Delete can be. - Truncate keeps the lock on table whereas Delete keeps the lock on ea

Explain the integrity constraints, Explain the integrity constraints: Not N...

Explain the integrity constraints: Not Null, Unique, Primary Key with an example each. Is the combination 'Not Null, Primary Key' a valid combination. Justify. Not Null - Shou

Develop and evaluate partial systems, Part 1: Security Plan Consider th...

Part 1: Security Plan Consider the Case study and identify 3 security requirements. For each of these security requirements: • Discuss the necessity for the feature and how

find a non-redundant cover and canonical cove, Given the following set of ...

Given the following set of functional dependencies {cf→ bg, g → d, cdg → f, b → de, d → c} defined on R(b,c,d,e,f,g) a. Is cf→ e implied by the FDs? b. Is dg a superkey?

Secondary indexes, Secondary Indexes Let consider the student database ...

Secondary Indexes Let consider the student database and its clustering index and primary (only one will be applicable at a time). Now consider the state when the database is to

A weak entity set and its identifying relationship, Q. Define a weak entit...

Q. Define a weak entity set and its identifying relationship. List the necessary conditions for a meaningful identifying relationship set of a weak entity set. Entity is a t

Compute natural join and outer join, For the relations R and S given below:...

For the relations R and S given below: R S A B C 1 4 7 2 5 8 3 6 9

Differance between procedural and non procedural dml, Differance between pr...

Differance between procedural and non procedural DML? Procedural and non procedural DML Procedural DML exactly what data is require and how to obtain those data. Non procedural

Why do so various organizations use mysql, Why do so various organizations ...

Why do so various organizations use MySQL? Advantages: Open source Highly efficient Offers a high scalability in terms of size and connectivity. Highly prote

Coursework, ERD Diagram of Medical Recruitment Agency?

ERD Diagram of Medical Recruitment Agency?

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages