NativeColumnEqExp implements NativeExp { @Override public String toSQL() { return right + " = " + left; } NativeColumnEqExp(String right, String left); @Override String toSQL(); @Override void setValues(NativeQuery query);  }
@Test public void testToSQL() { NativeColumnEqExp nativeColumnEqExp = new NativeColumnEqExp("col1", "col2"); Assert.assertEquals("col1 = col2", nativeColumnEqExp.toSQL()); }