How to update all records in a column based on condition?

[CUCOOPE]

Hi. Suppose I have a table called "My Table" like this:

ID(Auto generated)	Ball Number	Student_ID	Item_ID	Value
1	2	1234	12
2		2345	13

I'd like to patch the "Value" column of all the records based on whether the "Ball Number" column is blank. If it is blank, the "Value" should be Concatenate(Student_ID, Item_ID), but if it is not blank, the "Value" should be just the Student_ID.

I tried to use the following formula to achieve what I want:

ForAll('My Table', Patch('My Table', LookUp('My Table', ID=ThisRecord.ID), {

Value: If(!IsBlank(ThisRecord.'Ball Number'), ThisRecord.Student_ID, Concatenate(ThisRecord.Student_ID, ThisRecord.Item_ID))

}

But it keeps telling me "the function cannot operate on the same datasource that is used in Forall". I have read https://powerusers.microsoft.com/t5/Building-Power-Apps/Patch-the-same-data-source-as-in-Forall-loop... but I still have no idea how to make my code work. Can anyone help me? Thanks!

[timl · Accepted solution]

@CUCOOPE 

Rather than call ForAll, you can call UpdateIf to do a conditional update.

https://docs.microsoft.com/en-gb/powerapps/maker/canvas-apps/functions/function-update-updateif

UpdateIf('My Table',
         IsBlank('Ball Number'),
         {Value:Concatenate(Student_ID, Item_ID)}
)

[CUCOOPE]

Thanks!