How to use Empty Table Value in Logic

ATS16805

I'm basing my logic off of the assumption that a SELECT query will return a value of Zero, that is '0' for use in this array:

$check_day_id = "select day_id from days_table";
	$check_day_id_res = mysql_query($check_day_id) or die(mysql_error());
	// LOGIC= IF RESULTS <= 0 THEN DAY IS MONDAY ETC
	  $weekarray = array('Monday' => 0,'Tuesday' => 1,'Wednesday' => 2,'Thursday' => 3,'Friday' => 4,'Saturday' => 5,'Sunday' => 6); 
  foreach ($weekarray as $key => $val) { 
    if ($check_day_id_res == $val) { 
	 $day_of_week = $key; 
      break; 
    } 
  }

day_id value in my db table is:
INT not null primary key auto_increment

if i have rows in the days_table, the above array will work, allowing me to use $day_of_week, as in:
echo "<h1>Add an entry for".$day_of_week.":</h1>";
which will print: Add an entry for Thursday if there are three rows in the table at time of query

but, if i clear all rows from the table, my $day_of_week variable keeps "defaulting" to THursday!

i don't get it. why does it show thursday instead of Monday? what is this Array actually getting returned from the MySQL SELECT query above which would make it show THursday when there are no rows in my table?

ATS16805

If i print $check_day_id_res to the screen, i get Resource id #3

i am totally confused as to why that is happening... should i be getting, considering my EMPTY table, a result of Resource id #0 or Resource id #1, but why 3??

bpat1434

The resource ID number has nothing to do with your query, other than an identifier to values that mySQL returns. I.e. Resource ID #10 is equivilant to Resource ID #15081048.

Basically, you need to find out how many rows you have returned right? Check if there are no rows? If that's true, just add this line under your $check_day_id_res line:

$rows = mysql_num_rows($check_day_id_res)

If $rows == 0, then you can assume it to be monday. Otherwise, rows are returned. Then, you have to get the values into an array from the result using the [man]mysql_fetch_array[/man] function.

And are you 100% sure the database is completely empty?

~Brett

ATS16805

hmm... i think what you've told me will be my best choice.

i'm having difficulty because i think i've put the cart before the horse here a couple of different times. all i really want to do is be sure that i can properly populate my days of the week table w/out messing up the other tables...

i think my problem is that i'm tying myself to the thought that i must have monday=0, tuesday=1, wednesday=2, and so on, and i guess i don't really need that if my other tables and SQL queries are going to call the data using day_id #'s, and not names. i dunno... i have to think about it for a while... and try your suggestion, bpat1434

thanks!!

EDIT:
okay, i think i've got what's messing me up...
the data which will go into the "days of the week" table is conditional based upon which days have been filled, and which have not-- in other words, there's specific data for mon, specific for tues, etc.
How then, should i set up my form so that it knows to tell the user which days are available for data entry?

bpat1434

Research Joins and retrieving all the places where the value is NULL.

Joins (mySQL 5.0)
Read the first user comment....

~Brett

ATS16805

cool. i actually figured out how to overcome my error here.... at least for now, i've got 'er working. i used your row count method, and it works fine in my logic. i will take your suggestion and read the MySQL stuff soon though. FYI... i don't know if it matters, but i'm using MySQL 4.1.14

thanks so much!!!

EDIT:
just read that join thing... first user comment at your link.. about "petunia"? whoa! that is some profound stuff! i'll have to chew on that for a while... let alone put it in my app... do you mind elaborating on what you had in mind?