Python：奇怪的SQLite3查询结果

Question

我得到意想不到的结果与Python3中的SQLite3查询。

if first_waypoint_number < last_waypoint_number: 
     result = list(c.execute("SELECT WPNumber, WPID, ROUTE FROM rte WHERE ROUTE = ? AND WPNumber BETWEEN ? AND ?", (route, first_waypoint_number, last_waypoint_number))) 
     print(result) 
else: 
     result = list(c.execute("SELECT WPNumber, WPID, ROUTE FROM rte WHERE ROUTE = ? AND WPNumber BETWEEN ? AND ? ORDER BY WPNumber DESC", (route, first_waypoint_number, last_waypoint_number))) 
     print(result) 

第一个查询就像预期，并产生这样的结果：

[('A123', 25, 'WAYPOINTX'), ('A123', 26, 'WAYPONTY'), ('A123', 27, 'WAYPOINTZ')] 

第二个查询然而，产生一个空列表[]，而它应该返回按相反的顺序相同的列表。

我已经在SQLite3中测试了两个查询没有问题。

我在这里错过了什么吗？

Answer 1

The sqlite BETWEEN operator is equivalent to x>=y AND x<=z，所以当y > z时它什么都不匹配。

sqlite> create table foo (x int); 
sqlite> insert into foo values (1); 
sqlite> insert into foo values (2); 
sqlite> insert into foo values (3); 
sqlite> insert into foo values (4); 
sqlite> select * from foo; 
1 
2 
3 
4 
sqlite> select * from foo where x between 2 and 3; 
2 
3 
sqlite> select * from foo where x between 3 and 2; 
sqlite>