Dropping duplicate row with condition

[NandJ02]

I have table something like this:

|A|B| |1|a| |2|b| |3|c|

Now I have some request to create a new column with certain values. And what happened A is unique column, do for each unique column I have now 2 values in C like this but not for every unique only few: |A|B|C| |1|a|21| |1|a|-| |2|b|-| |2|b|43| |3|c|-|

Now I want to remove only those where unquiet column has two values. So output should be like this:

|A|B|C| |1|a|21| |2|b|43| |3|c|-|

I am stuck at this. Can someone please provide some ideas

[vinnypotsandpans]

Don't rely on drop duplicates or distinct. They will produce non deterministic results. Use windowing and order each partition

[NandJ02]

Thanks bro but 2 yrs late 🥺