• Home
  • Recent Q&A
  • Java
  • Cloud
  • JavaScript
  • Python
  • SQL
  • PHP
  • HTML
  • C++
  • Data Science
  • DBMS
  • Devops
  • Hadoop
  • Machine Learning
in Spark Sql by
Q:

SQL NULL Values

1 Answer

0 votes
by

What is a NULL Value?

A field with a NULL value is a field with no value.

If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value.

How to Test for NULL Values?

It is not possible to test for NULL values with comparison operators, such as =, <, or <>.

We will have to use the IS NULL and IS NOT NULL operators instead.

IS NULL Syntax

SELECT column_names
FROM table_name
WHERE column_name IS NULL;

IS NOT NULL Syntax

SELECT column_names
FROM table_name
WHERE column_name IS NOT NULL;

Related questions

0 votes
asked Sep 9, 2019 in Spark Sql by ivor2019
0 votes
asked Sep 9, 2019 in Spark Sql by ivor2019
...