Question

I want to delete rows from a table that has a column more than 7200 secs old.

The Query

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

where:

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

The query is meant to delete the row with log value 2011-06-25 09:56:51 because it is older than 7200 seconds but it does not.

What am I not getting right?

Answer 1

You have a space between DATE_ADD and the parenthesis: ( log, ....

Use DATE_ADD( log, ...

From 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.

And:

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.