Adding custom column

Can anyone help with the correct format for adding custom column?

I have a column named R which contains the following values
R
T1
T2
T3
Now i want to create a custom column Y1 which should show ABC text where Reason = T1
Expected Table
R | Y1
T1 | Z
T2
T3
image

Hi @Bhaumik1
Please read this: https://www.metabase.com/docs/latest/users-guide/expressions.html
You cannot return a boolean as a Custom Column.
And it's a column, so it will return Y1 for all rows, just like R.

Use something like this instead:
image

Obviously changing my Forename formula to your Reason