[RESOLVED] compare two fields

devil_online

Hi
I have an mysql database.
In a row i have two fields.

I want to insert a new row that field 1 and field 2 can not be equal.

like this table in the pic

How can I do that?

thanks

bpat1434

if($field_1 != $field_2)
{
  // They're not equal, insert
}

Is that what you were looking for?

devil_online

not quite.
I don't want that the field 1 is diferent from field 2.
what I want is that the combination field one and field 2 be unique
thanks

bpat1434

<?php
$next_insert = $_POST['field1'].'|'.$_POST['field2'];
$exists = array();

$query = "SELECT CONCAT(field1, '|', field2) as set FROM table";
$result = mysql_query($query);

while($row = mysql_fetch_array($result))
{
  $exists[] = $row['set'];
}

if(!in_array($next_insert, $exists))
{
  // Current set is not in the database
}

devil_online

thanks,
however I don't understand very well this line:

  

$query = "SELECT CONCAT(field1, '|', field2) as set FROM table";

my table is like this one in the file atached

how can I do it?

thanks

bpat1434

yes... CONCAT just concatinates the 3 strings (both fields and the "|" bar) into one string. so:

SELECT CONCAT(field1, '|', field2) as set FROM table

will return the following:

A|B
A|C
B|A
B|C
C|A
C|B

So you just get all that into an array, adn then see if your posted pair is in the array.

devil_online

ok
I see my problem.
I don't know why you put

 as set FROM table

Where do you get set

I don't have any set on the table ou if set is another row I don't understand why do you put it there

thanks

bpat1434

"as set" aliases the concatenated information. So I'm saying:

SELECT field1 and field2 from the database.
CONCATenate field1, field2, and "|" to make a string
AS set.

it's similar to saying:

$set = $field1.'|'.$field2

AS is basically a keyword meaning to alias the item before (table, column, string) as the keyword following "as". So in the loop of the row, you can reference the string as either $row[0] or $row['set'].

devil_online

sorry and thanks for your patiance but it gives this error:

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in F:\webs\names.php on line 9

line 9 have this code

while($row = mysql_fetch_array($result))

what i'm doing wrong?

thanks

bpat1434

echo out mysql_error() before your while loop

devil_online

it says:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'set FROM jogos' at line 1

tanks

bpat1434

woops... forgot "set" is a reserved word.... the query should be:

SELECT CONCAT(field1, '|', field2) as 'set' FROM table

devil_online

thanks it work very well