Question

我很惊讶mysql在运行mysql -e "$query"并输入查询时使用mysql在mysql控制台中评估同一语句的命令行。我有一个带有时间戳字段create_date的表。我以不同的方式运行相同的命令并获得不同的结果：

在mysql控制台中：

$ mysql -uuser -ppassword database1
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mysql> select DATE_ADD(create_time, INTERVAL DATEDIFF('2014-03-13', "2013-03-13") DAY) as date from table1;
+---------------------+
| date                |
+---------------------+
| 2014-03-08 00:00:11 |
| 2014-03-08 00:00:22 |
| 2014-03-10 00:00:33 |
| 2014-03-10 00:00:44 |
| 2014-03-12 00:00:55 |
| 2014-03-12 00:00:32 |
| 2014-03-08 00:00:42 |
| 2014-03-08 00:00:23 |
+---------------------+
8 rows in set (0.00 sec)

使用-e参数从命令行执行的相同查询会产生空结果：

$ mysql -uuser -ppassword urbanout_www -e 'select DATE_ADD(create_time, INTERVAL DATEDIFF('2014-03-13', "2013-03-13") DAY) as date from table1;'
+------+
| date |
+------+
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
+------+

对此有何解释？

Answer 1

当你在查询中使用单引号时，它们会终止shell的引用，而不是发送给MySQL。尝试：

$ mysql -uuser -ppassword urbanout_www -e 'select DATE_ADD(create_time, INTERVAL DATEDIFF("2014-03-13", "2013-03-13") DAY) as date from table1;'

MySQL：不同的评估命令行和mysql控制台

1 个答案: