question: void addCommand ( String sql ) { if ( sql == null ) { return ; } sql = sql . trim ( ) ; if ( sql . length ( ) == 0 ) { return ; } if ( commandHistory . size ( ) > MAX_HISTORY ) { commandHistory . remove ( 0 ) ; } int idx = commandHistory . indexOf ( sql ) ; if ( idx >= 0 ) { commandHistory . remove ( idx ) ; } commandHistory . add ( sql ) ; if ( server . isCommandHistoryAllowed ( ) ) { server . saveCommandHistoryList ( commandHistory ) ; } }
target:  Add a SQL statement to the history.