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Problem with code

Posted on 2014-03-28
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Last Modified: 2014-03-31
I keep getting an error on the last line of this code.  I'm sure it's something stupid that I can't see.

The error is:

Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in /home/langsyst/public_html/Walk_Map_Display.php on line 79

Line 79 is the last line in this code.

// ****************************************************
// * Get north and south from mapfile record.         *
// ****************************************************

$SqlString1 = "SELECT * FROM mapfile WHERE 
					`SEQ` LIKE \"$work\"
				and 
					`BNMB` = \"$address\"";	

$mapfile = mysql_query($SqlString1,$conn);
$ROW = Mysql_fetch_assoc($mapfile, MYSQL_BOTH);
$north = $ROW['NOR'];
$south = $ROW['SOU'];
$_SESSION['SOUTH'] = $north;
$_SESSION['NORTH'] = ($north - 1);

			
// ****************************************************
// * Get new address from north and south             *
// ****************************************************
$SqlString2 = "SELECT * FROM mapfile WHERE 
					`NOR= \"$north\"
				and 
					`SOU` = \"$south\"";
					echo "Str2 = ";
					echo $SqlString2;	
$mapfile2 = mysql_query($SqlString2,$conn);		
$ROW1 = Mysql_fetch_assoc($mapfile2, MYSQL_BOTH);

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Thanks
Glenn
0
Comment
Question by:breeze351
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8 Comments
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 39962488
The usual cause of this error is a failure in the query.  MySQL_Query() has return values and the script must test these to know if the function worked or failed.  Relying on the function to work without testing the return value is AntiPractice #24.

Examples showing how to test the return values from SQL functions are shown in this article.  Scan for Run the CREATE TABLE Query and Handle Errors/Exceptions and look for the way the sample scripts handle the return value from the query functions.
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/PHP_Databases/A_11177-PHP-MySQL-Deprecated-as-of-PHP-5-5-0.html
0
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39962507
A couple of errors.  Missing a 'backtik' after `NOR and I believe that data in MySQL statements is normally enclosed in single quotes.  Try this.
$SqlString2 = "SELECT * FROM mapfile WHERE 
	`NOR` =  '$north' AND `SOU` =  '$south'";

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LVL 110

Expert Comment

by:Ray Paseur
ID: 39962527
Dave: The missing backtick is a sure problem, and when Glenn adds the error visualization code after the query, that will jump out in a way that gives immediate feedback.  I think the embedded quotes can be either kind, so long as they are escaped, if necessary.  And the backticks are probably not needed at all, unless you've named a column using blanks or SQL reserved words.  NOR and SOU are not reserved words.
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LVL 83

Accepted Solution

by:
Dave Baldwin earned 500 total points
ID: 39962660
You're right about the quotes for strings.  https://dev.mysql.com/doc/refman/5.5/en/string-literals.html   I tend to prefer the single quotes in SQL statements in PHP because it makes it easier for me to read by avoiding all the \" escapes.
0
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 39962748
Yep, me too.  Just makes for fewer typographical errors, and anyone who knows me knows that I am the acknowledged King of Typos.
0
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39962826
Glenn, the reason that line is an error is because query on the line before failed.
0
 

Author Comment

by:breeze351
ID: 39967231
I figured it out.  It was the single quotes
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LVL 110

Expert Comment

by:Ray Paseur
ID: 39967477
You won't have to "figure it out" if you write the code following the standard best practices -- PHP will tell you!
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