Learning machine learning? Try my machine learning flashcards or Machine Learning with Python Cookbook.

What Happens When You Add NULL And Integer

17 Jun 2018

Question

What happens when you add a NULL value and an integer?

Answer

You get an error.

-- Drop table if exists
DROP TABLE IF EXISTS names;

-- Create table called names
CREATE TABLE names (
    -- string variable
    name varchar(255),
    -- integer variable
    score int
)

-- Insert into the table
INSERT INTO names (name, score)
-- two rows
VALUES
    (NULL, 1),
    ('Tommy', 1)

-- Add a column with a NULL value and a integer
SELECT
    name + score as results
FROM names

[42883] ERROR: operator does not exist: character varying + integer Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts. Position: 17