question: private boolean isIdentifier ( String token ) { int size = token . length ( ) ; for ( int i = 0 ; i < size ; i ++ ) { char c = token . charAt ( i ) ; if ( isOperator ( c ) ) return false ; } if ( token . startsWith ( "'" ) && token . endsWith ( "'" ) ) return false ; else { try { new BigDecimal ( token ) ; return false ; } catch ( NumberFormatException e ) { } } if ( isSQLFunctions ( token ) ) return false ; return true ; }
target:  Check if token is a valid sql identifier