SQLite Forum

Delete duplicate rows with an extra character
There are two statements.  

The first is an UPDATE statement which, for all rows where the player_tag startswith '#', removes the '#' character prefix.  For any row in which this change causes a conflict (duplicate player_tag after the update) the update is ignored.  This means that the only rows remaining where player_tag commences with '#' are duplicates to be deleted.

The second statement deletes all those duplicates.