Calculated Column checking against a multi-selection lookup

Question

FieldA is a lookup (to another SP list) with the option to select more than one choice from 9 options: let's call them 1 thru 9.

FieldB needs to be a calculated field that evaluates FieldA.

Certain values in FieldA trump others. Sort of like a roll-up, maybe.

• If there is a "6" selected, then nothing else matters and FieldB = Red.
• If there is not a 6 but there is a 2, then nothing else matters and FieldB = Blue.
• If there is neither a 6 nor a 2 but there is a 4, then nothing else matters and FieldB = Green.
• For any other scenario, FieldB = Yellow

I've done some simple nested if statements in calculate fields, but I've never done anything against a LOOKUP field and I don't know what complication the multi-select adds to this mess. Any functional samples?

Answer 1

Unfortunately, The Lookup fields can't be used in Column and List \ Library validation or Calculated Column.

Check THE SUPPORTED AND UNSUPPORTED COLUMNS IN SHAREPOINT CALCULATED COLUMN FORMULA

The alternative solutions.

• If you can change the lookup field to choice field with static options, so go ahead to use the choice field instead of lookup field, the choice field is supported in the Calculated Column

• If you can't, so try to create a workflow on item created/ changed that will read the lookup value and update it to a new field (single text) in the same list, so you can use this new field in your formula in Calculated Column.

Check the detail steps at USING LOOKUP FIELD IN SHAREPOINT CALCULATED COLUMN FORMULA