php warning mysql_fetch_assoc

by

Generally, the mysql_* functions are used as follows:

$id = 1234;
$query = 'SELECT name, genre FROM sometable WHERE id=' . $id;
// $query is a string with the MySQL query
$resource = mysql_query($query);
// $resource is a *MySQL result resource* - a mere link to the result set
while ($row = mysql_fetch_assoc($resource)) { 
    // $row is an associative array from the result set
    print_r($row);
    // do something with $row
}

If you pass something to mysql_fetch_assoc that is not a MySQL result resource (whether it’s a string, an object, or a boolean), the function will complain that it doesn’t know what to do with the parameter; which is exactly what you are seeing.

A common gotcha: you get this warning if you pass something (other than a valid query string) to mysql_query:

$id = null;
$query = 'SELECT name, genre FROM sometable WHERE id=' . $id;
$res = mysql_query($query); 
// $res === FALSE because the query was invalid
// ( "SELECT name, genre FROM sometable WHERE id=" is not a valid query )
mysql_fetch_assoc($res); 
// Warning: don't know what to do with FALSE, as it's not a MySQL result resource

More Related Contents:

  1. Prevent creating duplicate entries in PHP
  2. Query database then email posts from where user is subbed to
  3. Undefined index $_POST
  4. PHP Merging Row with same value (more than one column)
  5. Getting raw SQL query string from PDO prepared statements
  6. Correct way to use LIKE ‘%{$var}%’ with prepared statements?
  7. “Invalid parameter number: parameter was not defined” Inserting data
  8. Fatal error: Call to undefined function mysql_connect()
  9. Having issue with matching rows in the database using PDO
  10. How can I properly use a PDO object for a parameterized SELECT query
  11. How do I return integer and numeric columns from MySQL as integers and numerics in PHP?
  12. Whether to use “SET NAMES”
  13. Escaping single quote in PHP when inserting into MySQL [duplicate]
  14. How can I get enum possible values in a MySQL database?
  15. Doctrine Query Language get Max/Latest Row Per Group
  16. Inserting data using mysqli
  17. How can I decrypt a password hash in PHP?
  18. Is mysql_real_escape_string() necessary when using prepared statements?
  19. Updating from MYSQL to MYSQLI [duplicate]
  20. How to convert these strange characters? (ë, Ã, ì, ù, Ã)
  21. PDO error: SQLSTATE[HY000]: General error: 2031
  22. How to display image from database using php [duplicate]
  23. Simple PHP SQL login troubleshooting
  24. Change date format (in DB or output) to dd/mm/yyyy – PHP MySQL
  25. Create PHP array from MySQL column
  26. UNION syntax in Cakephp
  27. How do i search from serialize field in mysql database?
  28. Group mysql results by category and display them into groups under each category
  29. What is the PDO equivalent of function mysql_real_escape_string?
  30. PHP & mySQL: When exactly to use htmlentities?

Leave a Comment