The ISNULL operator in SQLite is used to check whether an expression is null or not. It returns true if the expression evaluates to NULL, and false otherwise.


The syntax of the ISNULL operator is as follows:

expression ISNULL

Where expression is any valid expression that can evaluate to NULL.


For example, consider the following SQLite query:

FROM mytable 
WHERE mycolumn ISNULL;

This query selects all the rows from the mytable table where the mycolumn column is null.

It’s worth noting that the ISNULL operator is equivalent to the IS NULL operator in SQLite. Therefore, the above query can also be written as follows:

FROM mytable 
WHERE mycolumn IS NULL;

Both of these queries will produce the same result.

In conclusion, the ISNULL operator is a simple yet useful tool for checking null values in SQLite. It allows developers to easily filter out null values from their queries and ensure that only non-null values are returned.