我有一列version
,它是varchar
,但包含double
值。当我试图获得最新(最大)版本时,我得到了不正确的结果。但当我做min时,我得到了正确的结果。
如何确定包含double的varchar列的顺序?
这是我桌子上的内容;
mysql> Desc Application;
+---------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+------------------+------+-----+---------+----------------+
| id | int(11) unsigned | NO | PRI | NULL | auto_increment |
| version | varchar(50) | YES | | NULL | |
+---------+------------------+------+-----+---------+----------------+
2 rows in set (0.01 sec)
mysql> select * from Application;
+----+---------+
| id | version |
+----+---------+
| 1 | 0.0.0 |
| 2 | 0.0.1 |
| 3 | 0.0.2 |
| 4 | 0.1.0 |
| 5 | 0.1.1 |
| 6 | 0.1.2 |
| 7 | 1.0.0 |
| 8 | 1.0.1 |
| 9 | 1.1.1 |
| 10 | 8.7.3 |
| 11 | 10.29.0 |
+----+---------+
11 rows in set (0.00 sec)
select max(version) from application;
+--------------+
| max(version) |
+--------------+
| 8.7.3 |
+--------------+
1 row in set (0.00 sec)
mysql> select version from application
-> ORDER BY version DESC
-> LIMIT 1;
+---------+
| version |
+---------+
| 8.7.3 |
+---------+
1 row in set (0.00 sec)
mysql> select min(version) from application;
+--------------+
| min(version) |
+--------------+
| 0.0.0 |
+--------------+
1 row in set (0.00 sec)
忘记这些是浮点的想法。MySQl将它们视为字符串,因为这是你告诉它的。
按字符顺序排序,8
最大,0
最小,因此您的结果是正确的。
如果您希望MySQL按数字顺序排序,请为其指定数字字段。或者,右对齐并零填充子字段-08.07.03
小于10.29.00