How to group by to just see value only one time?

I have a table with multiple columns i want to group this table by one Colum to see only the value once.

DF <- DF

`DF1 <- dbGetQuery(conO, paste0('SELECT PROMO_CODE, MERCHANT_CODE, DESCRIPTION FROM DF')) %>% group_by(MERCHANT_CODE)

`I want to see MERCHANT_CODE once

• i tired to grouping while selecting but gives me an error :

DF1 <- dbGetQuery(conO, paste0('SELECT PROMO_CODE, MERCHANT_CODE, DESCRIPTION FROM DF group by 2')) I gotError in dbSendQuery(conn, statement, ...) :Unable to retrieve JDBC result setJDBC ERROR: ORA-00933: SQL command not properly ended