If Select come back with No Data....?

Posted: Tue Aug 23, 2005 5:31 am

Greetings All,

I am pulling data from a database.....and what I would like to do is if the select statement comes back with no data....I would like to run another query so that is never comes back with no data.

My script runs....
[php]SELECT Time, Height FROM {$_POST['Station']} WHERE Date='$month/$day/$year'[/php]

If this comes back with no data...I would like it to do this...
[php]"SELECT Time, Height FROM {$_POST['Station']} where date = DATE_FORMAT(CURRENT_DATE(), '%c/%d/%Y')";[/php]

So it pulls the data from the current day.

How do I do that?

Thank You for your time!!

Dawg

registered · Site Admin Joined: Jun 04, 2004 Posts: 6437

Would this work?

Code:




SELECT Time, Height FROM {$_POST['Station']} WHERE Date='$month/$day/$year or DATE_FORMAT(CURRENT_DATE(), '%c/%d/%Y')

Posted: Wed Aug 24, 2005 7:11 am

That did not work along with about 500 other things I have tried so lets talk about what I am trying to do overall and see if I am going down the right path.

I have a form that generates an graph. This graph is saved in a cache file. HEre is the problem. Until they hit the submit button.....there is no data to pass to the rest of the script....to create the image...save the image....display the image.

I have varibles in the query that when you first go to the page come back as errors.....because you have not given it any data to fill the varibles.

How do I get around this?

How do I feed this script "Default" values IF the query comes up empty or IF the query has not run?

Thank You for your imput!

Dawg

Posted: Wed Aug 24, 2005 8:57 am

You could load defaults if the number of records returned in the query is zero. How to determine the number of records depends on the database you're using (MySQL, in this instance) and the access technique.

For standard MySQL, use the mysql_num_rows() function. e.g.

Code:

$rows = mysql_num_rows($result);


if ($rows == 0) {


..load defaults


}

Site Admin/Owner Joined: Aug 27, 2002 Posts: 17088

Try this

Code:

SELECT Time, Height FROM {$_POST['Station']} 


WHERE IF (Date='$month/$day/$year',Date='$month/$day/$year',date = DATE_FORMAT(CURRENT_DATE(), '%c/%d/%Y'));

I haven't tested it but it looks syntactically correct. For more information on MySQL Control Flow Functions, see http://dev.mysql.com/doc/mysql/en/control-flow-functions.html

Posted: Tue Aug 30, 2005 8:19 pm

Hey Dawg, did this work or not?