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?

Briefly describe concurrency execution, Briefly describe concurrency execut...

Briefly describe concurrency execution? Lock - based protocols Locks There are several modes in which a data item may be locked in this section we restrict our attention

Describe drop table command or cascade of sql, Describe DROP TABLE command ...

Describe DROP TABLE command of SQL along with both the options - CASCADE and RESTRICT. DROP TABLE command - This command drops the specified table. Dropping a table also dro

Explain derived and non-derived attribute, Explain Derived and Non-Derived ...

Explain Derived and Non-Derived Attribute? In few cases, two or more attribute values are related, for instance, Age and BirthDate attributes of a person. For specific person e

Define view? how it is related to data independence, A View may be defi...

A View may be defined of as a virtual table, that is, a table that does not really exist in its own right but is instead inferred from one or more underlying base data table. T

Remove partial dependancy, , write the relational schema, and draw the new ...

, write the relational schema, and draw the new dependency diagrams. Identify the normal forms for each table structure you created

Describe the algorithm to draw the dependency graph, Describe the algorithm...

Describe the algorithm to draw the dependency graph? Ans: Algorithm to draw Precedence Graph is like this: a. For every transaction T i participating in schedule S, make

Develop database academic assignment, Develop Database academic assignment ...

Develop Database academic assignment Project Description: For a provided set of instructions in a case study design Entity Relationship Diagram. - Entity Relationship Diag

What is meant by heuristic optimisation, What is meant by heuristic optimis...

What is meant by heuristic optimisation? Discuss the main heuristics that are applied during query optimisation. Ans: In heuristic optimization, heuristics are employed to r

Data files indices and data dictionary, The indices are accumulated in the ...

The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th

Describe the major steps in the implementation process, Question: (a) ...

Question: (a) One of the steps in the five-step problem-solving model is implementation. Implementation is considered a key step in the problem-solving model. A problem may be

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages