Create Table with condition on columns (to add)

Hello,

here's my situation : depending on user selection on a segment, I want to create a table that selects either the column1, either column2

Table = 
var user_choice = [sel] --= selectedvalue of a segment menu
return

if (user_choice="a",

SELECTCOLUMNS(
      
    data,"id",data[id],"DATA_LIB", data[COLONNE1],"VALUE",data[VALEUR])
    
,--else if = b 

SELECTCOLUMNS(  
    data,"id",data[id],"DATA_LIB", data[COLONNE2],"VALUE",data[VALEUR])
)

It's not working. Is it normal ?

Aim : I'd like to change my column reference in my bar charts depending the situation

(Today I duplicate the vizualiation and change the field)


Thanks !