understanding null vs blank or empty string values

NathanDorsch

I've always struggled with figuring out how to filter by fields with nulls vs blanks... for example, if I have a formula to identify if a field is null (this will not work with fields that contain empty strings or blank values, correct...?). I've tried using charlength functions to say (when charlength' is greater than 0 then not blank, etc....) but this doesn't seem to work with null values....

Is there a simple formula/way to identify if a field is blank (regardless of null or empty strings)?

GrantSmith

CASE WHEN COALESCE(TRIM(`field`), '') = '' THEN 'Blank' ELSE 'Not Blank' END

COALESCE will return the first non-null value it finds, used in this case it's saying if the field is null return an empty string. I've wrapped the field in a trim to remove any leading or trailing whitespaces in case someone has a value of all spaces to ignore. Then it is compared to an empty string after it's been converted.

A more verbose way would be:

CASE WHEN `field` IS NULL or TRIM(`field`) = '' THEN 'Blank' ELSE 'Not Blank' END

NULL is a very specific value. The only way to check for null is to use IS NULL or a COALESCE / IFNULL function to default it to a specific value and compare that value.

Most functions you use on NULL or comparison will result in a NULL value back because NULL represents the absence of data.

GrantSmith

CASE WHEN COALESCE(TRIM(`field`), '') = '' THEN 'Blank' ELSE 'Not Blank' END

COALESCE will return the first non-null value it finds, used in this case it's saying if the field is null return an empty string. I've wrapped the field in a trim to remove any leading or trailing whitespaces in case someone has a value of all spaces to ignore. Then it is compared to an empty string after it's been converted.

A more verbose way would be:

CASE WHEN `field` IS NULL or TRIM(`field`) = '' THEN 'Blank' ELSE 'Not Blank' END

NULL is a very specific value. The only way to check for null is to use IS NULL or a COALESCE / IFNULL function to default it to a specific value and compare that value.

Most functions you use on NULL or comparison will result in a NULL value back because NULL represents the absence of data.