Learn about SQL IS NULL and IS NOT NULL with the help of examples. Learn how to use the SQL IS NULL and IS NOT NULL operators to filter data based on whether or not a column contains a value.
In SQL, IS NULL
and IS NOT NULL
are used to check if a column in a table contains a NULL value or not.
In SQL, the IS NULL
condition is used to select rows if the specified field is NULL
. It has the following syntax:
SELECT column1, column2, ...
FROM table
WHERE column_name IS NULL;
Here,
column1, column2, ...
are the table columnstable
is the table name from where we select the datacolumn_name
is the name of the column you want to check for NULL
For example,
-- select rows with NULL email values
SELECT *
FROM Employee
WHERE email IS NULL;
Here, the above SQL query retrieves all the rows from the Employee
table where the value of the email
column is NULL
.
Example: IS NULL in SQL
Note: Empty values are considered NULL
. However, space and 0 are not considered NULL
.
In SQL, the IS NOT NULL
condition is used to select rows if the specified field is NOT NULL
. It has the following syntax:
SELECT column1, column2, ...
FROM table
WHERE column_name IS NOT NULL;
Here,
column1, column2, ...
are the table columnstable
is the table name from where we select the datacolumn_name
is the name of the column you want to check for NOT NULL
For example,
-- select rows where email is not NULL
SELECT *
FROM Employee
WHERE email IS NOT NULL;
Here, the above SQL query retrieves all the rows from the Employee
table where the value of the email
column is NOT NULL
.
Example: IS NOT NULL in SQL
We can use the COUNT() function with IS NULL
to count the number of rows with an empty field. For example,
SELECT COUNT(*)
FROM Employee
WHERE email IS NULL;
Here, the SQL query retrieves the count of all the rows from the Employee
table where the value of the email
column is NULL
.
Example: IS NULL with COUNT() in SQL
Similarly, we can use the COUNT()
function with IS NOT NULL
to count the number of non-empty fields.
#sql