SQL Query to describe ‘NULL’ value -Best example

The below is the data in sample table of name ‘DATA’. The question is how NULL performs in expressions.

Example Table and an SQL Query to check NULL

Table: DATA

COL1     COL2    COL3

1           2          NULL

SQL Query:

SELECT 
col1 + col2, col2 + col3, col1 + col2 / col3 
FROM data;

Q) What are the three possible values returned by the sample SQL query above?

  • Choice 1 : 3, NULL, 0
  • Choice 2 : 3, 2, 0
  • Choice 3 : 3, 2, 3
  • Choice 4 : 3, NULL, NULL
  • Choice 5 : 3, 2, NULL

The correct answer is ‘Choice 4’.