In Hive, nvl() is a function that can be used to handle null values in queries. The nvl() function takes two arguments – the first argument is the expression that you want to check for null values, and the second argument is the value that you want to return if the expression is null.
Here’s an example of how to use the nvl() function to handle null values in a Hive query:
SELECT name, nvl(age, 0) as age FROM customers;
In this example, we’re selecting the name and age columns from the customers table. If the age column contains null values, the nvl() function will replace them with a default value of 0. The result set will contain the name column and the age column, with null values replaced by 0.
The nvl() function can be used in various ways to handle null values in Hive queries. For example, you can use it to replace null values with default values, or to perform calculations that involve null values. Here’s another example:
SELECT name, nvl(salary, 0) * 2 as double_salary FROM employees;
In this example, we’re selecting the name and salary columns from the employees table. If the salary column contains null values, the nvl() function will replace them with a default value of 0. We’re then multiplying the resulting value by 2, to calculate the double of the salary. The result set will contain the name column and the double_salary column, with null values replaced by 0.
Using the nvl() function can be a useful way to handle null values in Hive queries, allowing you to perform calculations and transformations on data that may contain missing values.