MySQL查询未返回任何结果

Question

I am testing an application which connects to database and retrieve results. It uses PHP, and Joomla framework. The thing is that if I put a query as

$query = "SELECT * FROM #__coupon_member_details";
$this->_db->setQuery($query);        
$result = $this->_db->query();
$number = mysql_num_rows($result);
if($number == 0 ){
        JFactory::getApplication()->enqueueMessage("no data returned by db");
}else{
        JFactory::getApplication()->enqueueMessage($number);
}

The above code gives message "no data returned by db" except the fact that the table contains a lot of data (200+ rows).

If I put invalid table name as #__coupon_member_details123 , then it produces an error saying "Table does not exist".

I fail to understand what is wrong ?

Answer 1

In Joomla you have to use correct Joomla API which goes like this. mysql_num_rows equivalent in Joomla is getNumRows

$query = $this->_db->getQuery(true);
$query = "SELECT * FROM #__coupon_member_details";
$this->_db->setQuery($query);
$result = $this->_db->query();
$numRows = $this->_db->getNumRows();
if($numRows == 0 ){
        JFactory::getApplication()->enqueueMessage("no data returned by db");
}else{
        JFactory::getApplication()->enqueueMessage($number);
}

Answer 2

I would do it this way:

$query = "SELECT * FROM #__coupon_member_details";
$this->_db->setQuery($query);
$arrResult = $this->_db->loadAssocList();
$intCountResults = count($arrResult);

The above query will return the data in $arrResult , and the number of results in $intCountResults .

If you only want the number, then I suggest you change the above to:

$query = "SELECT COUNT(*) AS `totalcount` FROM #__coupon_member_details";
$this->_db->setQuery($query);
$intCountResults = $this->_db->loadResult();

This is better and is scalable. Even better you could do something like SELECT count(id) instead of SELECT COUNT(*) (if you have an id field).