Syntax for empty

What is the syntax to custom filter a field for all of the values that are empty (blank)? I tried ISEMPTY([GROUP_ID]), but it didn't work.

Accepted answers

I'd go for

IsNull([Group_ID]) OR Trim([Group_ID])=''

assuming you want both nulls and whitespace

ISEMPTY will only match NULL fields and fields that equal ''

To match NULL fields, fields that equal '', or fields that contain only spaces, try this in the formula tool

REGEX_Match([test_string], '\s*')

I'd go for

IsNull([Group_ID]) OR Trim([Group_ID])=''

assuming you want both nulls and whitespace

I filtered with GROUP_ID = "" and this seemed to work.