SELECT查询是否可能在Joomla DB中插入数据？

Question

I need to check whether a value is in a DB. I am using

$db = JFactory::getDBO();
$query = $db->getQuery( true );

$query->select($db->quoteName('id'));
$query->from($db->quoteName('#__tablename'));
$query->where($db->quoteName('fieldname') . ' = ' . $db->quoteName($valuetocheck));
$db->setQuery($query);
$id = $db->loadResult();

echo "value = " . $id;

if($id) {/*action if the value already exists*/} else {/*...*/}

The problem is that every new value that I set to $valuetocheck is actually being inserted into the table. If I set a value that does not exist yet, it gets inserted, and so I always get a valid $id and cannot proceed to the else {}.

Is that possible? Is there any workaround to check whether a value is already inside?

Answer 1

Try this,

A SELECT query never insert any value to the DB If the data's are inserting in the table its should be somewhere else. Also instead of checking $id value you can check numrows as below.

$db = JFactory::getDBO();
$query = $db->getQuery( true );

$query->select($db->quoteName('id'));
$query->from($db->quoteName('#__tablename'));
$query->where($db->quoteName('fieldname') . ' = ' . $db->quoteName($valuetocheck));
$db->setQuery($query);
$db->query();
if($db->getNumRows() >0){
 //Data found
}
else{
 //Nod Data found
}

Hope it helps..