Generating Query Results
There are several ways to generate query results:
result()
This function returns the query result as an array of objects, or an empty array on failure. Typically you'll use this in a foreach loop, like this:
$query = $this->db->query("YOUR QUERY");
foreach ($query->result() as $row)
{
echo $row->title;
echo $row->name;
echo $row->body;
}
The above function is an alias of result_object().
If you run queries that might not produce a result, you are encouraged to test the result first:
$query = $this->db->query("YOUR QUERY");
if ($query->num_rows() > 0)
{
foreach ($query->result() as $row)
{
echo $row->title;
echo $row->name;
echo $row->body;
}
}
You can also pass a string to result() which represents a class to instantiate for each result object (note: this class must be loaded)
$query = $this->db->query("SELECT * FROM users;");
foreach ($query->result('User') as $row)
{
echo $row->name; // call attributes
echo $row->reverse_name(); // or methods defined on the 'User' class
}
result_array()
This function returns the query result as a pure array, or an empty array when no result is produced. Typically you'll use this in a foreach loop, like this:
$query = $this->db->query("YOUR QUERY");
foreach ($query->result_array() as $row)
{
echo $row['title'];
echo $row['name'];
echo $row['body'];
}
row()
This function returns a single result row. If your query has more than one row, it returns only the first row. The result is returned as an object. Here's a usage example:
$query = $this->db->query("YOUR QUERY");
if ($query->num_rows() > 0)
{
$row = $query->row();
echo $row->title;
echo $row->name;
echo $row->body;
}
If you want a specific row returned you can submit the row number as a digit in the first parameter:
$row = $query->row(5);
You can also add a second String parameter, which is the name of a class to instantiate the row with:
$query = $this->db->query("SELECT * FROM users LIMIT 1;");
$query->row(0, 'User')
echo $row->name; // call attributes
echo $row->reverse_name(); // or methods defined on the 'User' class
row_array()
Identical to the above row() function, except it returns an array. Example:
$query = $this->db->query("YOUR QUERY");
if ($query->num_rows() > 0)
{
$row = $query->row_array();
echo $row['title'];
echo $row['name'];
echo $row['body'];
}
If you want a specific row returned you can submit the row number as a digit in the first parameter:
$row = $query->row_array(5);
In addition, you can walk forward/backwards/first/last through your results using these variations:
$row = $query->first_row()
$row = $query->last_row()
$row = $query->next_row()
$row = $query->previous_row()
By default they return an object unless you put the word "array" in the parameter:
$row = $query->first_row('array')
$row = $query->last_row('array')
$row = $query->next_row('array')
$row = $query->previous_row('array')
Result Helper Functions
$query->num_rows()
The number of rows returned by the query. Note: In this example, $query is the variable that the query result object is assigned to:
$query = $this->db->query('SELECT * FROM my_table');
echo $query->num_rows();
$query->num_fields()
The number of FIELDS (columns) returned by the query. Make sure to call the function using your query result object:
$query = $this->db->query('SELECT * FROM my_table');
echo $query->num_fields();
$query->free_result()
It frees the memory associated with the result and deletes the result resource ID. Normally PHP frees its memory automatically at the end of script execution. However, if you are running a lot of queries in a particular script you might want to free the result after each query result has been generated in order to cut down on memory consumptions. Example:
$query = $this->db->query('SELECT title FROM my_table');
foreach ($query->result() as $row)
{
echo $row->title;
}
$query->free_result(); // The $query result object will no longer be available
$query2 = $this->db->query('SELECT name FROM some_table');
$row = $query2->row();
echo $row->name;
$query2->free_result(); // The $query2 result object will no longer be available