How do I change all empty strings to NULL in a table?

Question

I have a legacy table with about 100 columns (90% nullable). In those 90 columns I want to remove all empty strings and set them to null. I know I can:

updat         


        

Answer 1

You could write a simple function and pass your columns to it:

Usage:

SELECT
  fn_nullify_if_empty(PotentiallyEmptyString)
FROM
  table_name
;

Implementation:

DELIMITER $$
CREATE FUNCTION fn_nullify_if_empty(in_string VARCHAR(255))
  RETURNS VARCHAR(255)
  BEGIN
    IF in_string = ''
      THEN RETURN NULL;
      ELSE RETURN in_string;
    END IF;
  END $$
DELIMITER ;