Calculated field - Calculate on first instance of text and not change after

[MelissaDa]

Hi community! I have a calculated field that determines if a request queue issue was submitted via email or the form. (Formula below). It's working correctly but if someone changes the queue topic on the issue, it recalculates and changes the value. I'd like for it to calculate the first time and then never change. I know this is possible but I don't know how. Can anyone help?

IF({queueTopicID}="6335e54d00928f36d0689d4974d7f342", "Email", "Form")

[William-- · Accepted solution]

To lock a calculated field to its first value, it needs to reference itself to see if a value has already been written.
 
In your example, it would look like this (presuming the name of your calculated field is something like "Source"):

IF(ISBLANK({DE:Source}),IF({queueTopicID}="6335e54d00928f36d0689d4974d7f342","Email","Form"),{DE:Source})

The logic is: "if the calculated field "Source" is blank, give it a value using this IF statement. If "Source" is not blank (because a value has already been written to it), keep the existing value."

[MelissaDa]

Thank you so much! This worked perfectly!