@Override
	public String toString() {
		return toString(null);
	}
@Test
	public void toStringTest() {
		Condition conditionNull = new Condition("user", null);
		assertEquals("user IS NULL", conditionNull.toString());

		Condition conditionNotNull = new Condition("user", "!= null");
		assertEquals("user IS NOT NULL", conditionNotNull.toString());

		Condition condition2 = new Condition("user", "= zhangsan");
		assertEquals("user = ?", condition2.toString());

		Condition conditionLike = new Condition("user", "like %aaa");
		assertEquals("user LIKE ?", conditionLike.toString());

		Condition conditionIn = new Condition("user", "in 1,2,3");
		assertEquals("user IN (?,?,?)", conditionIn.toString());

		Condition conditionBetween = new Condition("user", "between 12 and 13");
		assertEquals("user BETWEEN ? AND ?", conditionBetween.toString());
	}