Newbie.. if else problem

Anon

Hello,

I'm new to PHP and went out and bought 3 books that I've spent the last week and a half pouring over, only to get caught up over a basic if... else statement.

I have a links database that I want a user to search to make sure his or her URL does not already exist before filling out the form to add.

So, I created the following form for test purposes (no fancy HTML yet):

<BODY>
<FORM ACTION="link_validation.php" METHOD="POST">
Please enter your URL to see if it is already in our database.<BR>
<INPUT TYPE="text" NAME="submitURL"><BR>
<INPUT TYPE="submit">
</FORM>
</BODY>

It goes to the link_validation.php script
that I've pasted below.

If the link is there, everything works. The information is posted onto the webpage.
But, if the link is not there, nothing appears.

Can anyone tell me what the heck I'm doing wrong here?

$display_block2 .= "
<strong> Your submission does not exist in our database.</strong>";
}
?>

<HEAD>
<TITLE>Link Existance</TITLE>
</HEAD>

<BODY>

<?php

if ($submitURL = "links.url")
print("$display_block1");
else
{
print("$display_block2");
}
?>
</BODY>

Thanks in advance for any suggestions.

Mada

Anon

if ($submitURL = "links.url")

should be

if($submitURL == "links.url")

Anon

Graeme,

Thanks for your suggestion, but when I do this, and enter a link that is in the database, it says that it isn't. If I enter a link that isn't in the database, I get a blank page.

To see what I mean, please go to

http://www.ohrats.net/links/add_link.html

http://www.geocities.com/marion7282
is in the database.

http://www.yahoo.com
is not in the database.

Any advise would be appreciated.

Thanks for your time!

Mada

Anon

But Graeme is right about part of your problem. PHP borrows
C's favorite gotcha (assignments are expressions, too) so that

    if ($submitURL = "links.url")

is perfectly valid PHP syntax. What it means is not what you
intended (which is obviously a comparison) but rather it first
assigns a new value to $submitURL and then tests to see if
the value of $submitURL is false -- which of course it isn't since
you just gave it a value.

This is why if a link doesn't exist, you get a blank page: the
true branch of the test executes, but $displayblock1 has
never been assigned any value.

As for the opposite problem, the comparison

    if ($submitURL = "links.url")

is meaningless; you're seeing if the user's entry is literally equal
to "links.url". You cannot get at the value of a column that way.
Instead, when you execute the loop through the results, you
retrieve the value into $url:

    $url = $row['url'];

You could compare to that, but it makes a lot more sense to me
to simply ask MySQL how many rows there are in the result:

    $result = @($sql,$connection);
    $result_count = mysql_num_rows($result);
    ...
    if ($result_count > 0)
      { / show results of lookup / }
    else
      { echo "New url<br>"; }

Anon

TRY:

if ($submitURL == $url) {
print $display_block1;
}
else {
print $display_block2;
}

Anon

Thank you all for your suggestions, but none of them worked to display the link that is not in the database....

Any other suggestions, or do you guys know of another way to write the code besides an if/else statement?

Again, thanks for all of your help.

Mada

Anon

I think Kirk's explaination was right on. Your main problem of having a blank page if there was no hit in the database is because you are building your html string inside the WHILE loop. That loop is never entered if there was no hit in the database. If you build the $display_block2 variable outside the wile loop and change the "IF" to look like the code I posted above, it should work.

Go ahead and modify the code as suggested. If it still doesn't work, post the modified code and I can look at it. I am sure there is nothing wrong with the IF construct of php...

Anon

Richard,

I'm not sure if I got this right, but this did not work. From what I got from your reply, I need to build my display blocks in
<?

Thanks for the help!

Mada

<?
$db_name = "ohrats_net";
$table_name = "links";
$connection = @mysql_connect("localhost", "username", "password")
or die("Couldn't connect.");
$db = @mysql_select_db($db_name, $connection)
or die("Couldn't select database.");
$sql = "SELECT *
FROM $table_name Where links.url = \"$submitURL\" ";
$result = @($sql,$connection)
or die("Couldn't execute query.");
while ($row = mysql_fetch_array($result)) {
$id = $row['id'];
$site_title = $row['site_title'];
$url = $row['url'];
$description = $row['description'];
$category = $row['category'];
$subcategory = $row['subcategory'];
?>
<?
$display_block1 .= "
<center><font face=arial size=3>Your URL already exists!</font></center><br>
<font face=arial size=2>Please review your link below:</font><br> <br><br>
<font face=arial size=2><strong><a href=\"$url\" Target=\"blank\">$site_title</a></strong><br>$description <br>Category: $category/$subcategory<br><br></font>
<font face=arial size=2>Is this link acceptable? <a href=\"http://www.ohrats.net/links/thank_you.php\">Yes</a> <a href=\"http://www.ohrats.net/links/modify.php?site_title=$site_title\">No</a><br><br>
";

$display_block2 .= "
<strong> Your submission does not exist in our database.</strong>";
}
?>

<HEAD>
<TITLE>Link Existance</TITLE>
</HEAD>

<BODY>

<?php

if ($submitURL = "links.url")
print("$display_block1");
else
{
print("$display_block2");
}
?>
</BODY>

Anon

Hey, I figured out what you wanted. Took awhile. Pasting code in case someone else has a similar problem.

Thanks all for your help!

Mada

$display_block2 .= "
<strong> Your submission does not exist in our database.</strong>";
$result = @($sql,$connection)
or die("Couldn't execute query.");
while ($row = mysql_fetch_array($result)) {
$id = $row['id'];
$site_title = $row['site_title'];
$url = $row['url'];
$description = $row['description'];
$category = $row['category'];
$subcategory = $row['subcategory'];
$display_block1 .= "
<center><font face=arial size=3>Your URL already exists!</font></center><br>
<font face=arial size=3>Please review your link below:</font><br> <br><br>
<font face=arial size=2><strong><a href=\"$url\" Target=\"blank\">$site_title</a></strong><br>$description <br>Category: $category/$subcategory<br><br></font>
<font face=arial size=2>Is this link acceptable? <a href=\"http://www.ohrats.net/links/thank_you.php\">Yes</a> <a href=\"http://www.ohrats.net/links/modify.php?site_title=$site_title\">No</a><br><br>
";

}
?>

<HEAD>
<TITLE>Validating Link Existance</TITLE>
</HEAD>

<BODY>

<?php

if ($submitURL == $url) {
print $display_block1;
}
else {
print $display_block2;
}
?>
</BODY>

Anon

New problem... and was rather pleased that I didn't have any errors...

As you know from the messages above, I want a user to make sure his or her URL is not in the database before adding. So he or she enters the url and if it is in the database, it exhibits the link...

They then have the choice to modify it, if it's not correct.

I thought everything was alright, because the script spits back their modifications, but does not actually correct the info in the database...

Where am I going wrong here? I've checked the script repeatedly against the example in the book, and it looks correct.

Codes below (this goes from link_validation.php [above] to modify.php below then to modify_action.php below.

modify.php

<?
$db_name = "ohrats_net";
$table_name = "links";

$connection = @mysql_connect("localhost", "username", "password")
or die("Couldn't connect.");
$db = @mysql_select_db($db_name, $connection)
or die("Couldn't select database.");
$sql = "SELECT *
FROM $table_name Where site_title = \"$site_title\" ";
$result = @($sql,$connection)
or die("Couldn't execute query.");
while ($row = mysql_fetch_array($result)) {
$id = $row['id'];
$site_title = $row['site_title'];
$url = $row['url'];
$description = $row['description'];
$category = $row['category'];
$subcategory = $row['subcategory'];

$modify_block = "
<form method= \"post\" action=\"modify_action.php\">
<input type =\"hidden\" name=\"id\" value=\"$id\">
<table>
<tr>
<td>Site Title</td>
<td><input type=\"text\" name=\"site_title\" value=\"$site_title\"></td>
</tr>
<tr>
<td>URL</td>
<td><input type=\"text\" name=\"url\" value=\"$url\"></td>
</tr>
<tr>
<td>Description</td>
<td><input type=\"text\" name=\"description\" value=\"$description\"></td>
</tr>
<tr>
<td>Category</td>
<td><input type=\"text\" name=\"category\" value=\"$category\"></td>
</tr>
<tr>
<td>SubCategory</td>
<td><input type=\"text\" name=\"subcategory\" value=\"$subcategory\"></td>
</tr>
<tr>
<td></td>
<td align=\"right\"><input type=\"submit\"></td>
</tr>
</table>
</form>
";
}
?>

<HEAD>
<TITLE>Modify Link Existance</TITLE>
</HEAD>

<BODY>
<?

print("$modify_block");

?>
</BODY>

modify_action.php

<?
$db_name = "ohrats_net";
$table_name = "links";

$connection = @mysql_connect("localhost", "username", "password")
or die("Couldn't connect.");
$db = @mysql_select_db($db_name, $connection)
or die("Couldn't select database.");
$sql = "UPDATE $table_name
SET
site_title = \"$site_title\",
url = \"$url\",
description = \"$description\",
category = \"$category\",
subcategory = \"$subcategory\",
WHERE id = \"$id\"
";
$result = @($sql,$connection)
;

$modify_complete = "
<font face=arial size=2>Your Link has been modified:</font><br> <br><br>
<font face=arial size=2><strong><a href=\"$url\" Target=\"blank\">$site_title</a></strong><br>$description <br>Category: $category/$subcategory<br><br></font>
";

<HEAD>
<TITLE>Modified Link Existance</TITLE>
</HEAD>

<BODY>

<?php

print("$modify_complete");

?>
</BODY>

Anon

Actually, the problem is not with the "<?" or "?>", it is with the WHILE block and the IF/ELSE blocks...

================
<?

$db_name = "ohrats_net";
$table_name = "links";
$connection = @mysql_connect("localhost", "username", "password") or die("Couldn't connect.");
$db = @mysql_select_db($db_name, $connection) or die("Couldn't select database.");
$sql = "SELECT * FROM $table_name Where links.url = \"$submitURL\" ";

// So far, so good. Now you are going to execute the sql and retrieve the results...

$result = @($sql,$connection) or die("Couldn't execute query.");

// This WHILE loop is where part of your problem is.
// If there was no data returned from your querry, the block (inside the {}) is never executed...

while ($row = mysql_fetch_array($result)) {
$id = $row['id'];
$site_title = $row['site_title'];
$url = $row['url'];
$description = $row['description'];
$category = $row['category'];
$subcategory = $row['subcategory'];

$display_block1 .= " <center>Your URL already exists!</center><br> Please review your link below:<br> <br><br> <strong><a href=\"$url\" Target=\"blank\">$site_title</a></strong><br>$description <br>Category: $category/$subcategory<br><br> Is this link acceptable? <a href=\"http://www.ohrats.net/links/thank_you.php\">Yes</a> <a href=\"http://www.ohrats.net/links/modify.php?site_title=$site_title\"> No</a><br><br>";

// You need to end the WHILE block here; before you define display block 2...

}

// Now you define display block 2 outside the WHILE loop, so it is defined
// whether there was a hit in the database or not....

$display_block2 .= "<strong> Your submission does not exist in our database.</strong>";

<HEAD>
<TITLE>Link Existance</TITLE>
</HEAD>

<BODY>

<?php

// change your comparison so that it actually compares two variables, not
// assign "links.url" literal to $submitURL variable....

if ($submitURL == $url) {
print $display_block1;
}

// since you moved assigning display block 2 outside the WHILE loop above,
// it now has something in it to print if there was no hit in the database!
else {
print $display_block2;
}

?>
</BODY>

=====================

I put the explainations in comment lines in the code above, so if you cut and paste it (and then adjust for linefeeds) it should work for you.

Let me know...

-- Rich --

Anon

You probably have a syntax error in you update SQL. If you take the "@" off the from of the "mySQL_querry()" you will see it. My guess is that it is the comma following:

subcategory = \"$subcategory\"

-- Rich --

Anon

Richard,

Got it!

Thanks so much for your help.

Mada