mysql - mysql 日期查询失败

Question

我想从表中删除包含超过 7200 秒的列的行。

查询

mysql_query("delete from logged where DATE_ADD ( log, INTERVAL $this->loginDuration SECOND) < NOW()",$this->link);

地点:

name of table = logged; 
name of column = log; 
$this->loginDuration = 7200; 

The value of log in db: 2011-06-25 09:56:51.
Todays date and time [ Now() ] : 2011-07-05 11:39:02

该查询旨在删除日志值为 2011-06-25 09:56:51 的行，因为它早于 7200 秒，但事实并非如此。

我哪里做错了？

Answer 1

DATE_ADD 和括号之间有一个空格:( log, ...。

使用DATE_ADD(log, ...

来自MySQL docs, Functions and Operators :

Note

By default, there must be no whitespace between a function name and the parenthesis following it. This helps the MySQL parser distinguish between function calls and references to tables or columns that happen to have the same name as a function. However, spaces around function arguments are permitted.

还有:

You can tell the MySQL server to accept spaces after function names by starting it with the --sql-mode=IGNORE_SPACE option. (See Section 5.1.6, “Server SQL Modes”.) Individual client programs can request this behavior by using the CLIENT_IGNORE_SPACE option for mysql_real_connect(). In either case, all function names become reserved words.