CodeIgniter – Generating Query Results

CodeIgniter – Generating Query Results

Result Arrays

result()

This method 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 method is an alias of result_object().

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 $user)
{
        echo $user->name; // access attributes
        echo $user->reverse_name(); // or methods defined on the 'User' class
}

result_array()

This method 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'];
}

Result Rows

row()

This method 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");

$row = $query->row();

if (isset($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;");
$row = $query->row(0, 'User');

echo $row->name; // access attributes
echo $row->reverse_name(); // or methods defined on the 'User' class

row_array()

Identical to the above row() method, except it returns an array. Example:

$query = $this->db->query("YOUR QUERY");

$row = $query->row_array();

if (isset($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_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’)

Note

All the methods above will load the whole result into memory (prefetching). Use unbuffered_row() for processing large result sets.

unbuffered_row()

This method returns a single result row without prefetching the whole result in memory as row() does. If your query has more than one row, it returns the current row and moves the internal data pointer ahead.

$query = $this->db->query("YOUR QUERY");

while ($row = $query->unbuffered_row())
{
        echo $row->title;
        echo $row->name;
        echo $row->body;
}

You can optionally pass ‘object’ (default) or ‘array’ in order to specify the returned value’s type:

$query->unbuffered_row();               // object
$query->unbuffered_row('object');       // object
$query->unbuffered_row('array');        // associative array

Custom Result Objects

You can have the results returned as an instance of a custom class instead of a stdClass or array, as the result() and result_array() methods allow. This requires that the class is already loaded into memory. The object will have all values returned from the database set as properties. If these have been declared and are non-public then you should provide a __set() method to allow them to be set.

Example:

class User {

        public $id;
        public $email;
        public $username;

        protected $last_login;

        public function last_login($format)
        {
                return $this->last_login->format($format);
        }

        public function __set($name, $value)
        {
                if ($name === 'last_login')
                {
                        $this->last_login = DateTime::createFromFormat('U', $value);
                }
        }

        public function __get($name)
        {
                if (isset($this->$name))
                {
                        return $this->$name;
                }
        }
}

In addition to the two methods listed below, the following methods also can take a class name to return the results as: first_row(), last_row(), next_row(), and previous_row().

custom_result_object()

Returns the entire result set as an array of instances of the class requested. The only parameter is the name of the class to instantiate.

Example:

$query = $this->db->query("YOUR QUERY");

$rows = $query->custom_result_object('User');

foreach ($rows as $row)
{
        echo $row->id;
        echo $row->email;
        echo $row->last_login('Y-m-d');
}

custom_row_object()

Returns a single row from your query results. The first parameter is the row number of the results. The second parameter is the class name to instantiate.

Example:

$query = $this->db->query("YOUR QUERY");

$row = $query->custom_row_object(0, 'User');

if (isset($row))
{
        echo $row->email;   // access attributes
        echo $row->last_login('Y-m-d');   // access class methods
}

You can also use the row() method in exactly the same way.

Example:

$row = $query->custom_row_object(0, 'User');

Result Helper Methods

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();

Note

Not all database drivers have a native way of getting the total number of rows for a result set. When this is the case, all of the data is prefetched and count() is manually called on the resulting array in order to achieve the same result.

num_fields()

The number of FIELDS (columns) returned by the query. Make sure to call the method using your query result object:

$query = $this->db->query('SELECT * FROM my_table');

echo $query->num_fields();

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 consumption.

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

data_seek()

This method sets the internal pointer for the next result row to be fetched. It is only useful in combination with unbuffered_row().

It accepts a positive integer value, which defaults to 0 and returns TRUE on success or FALSE on failure.

$query = $this->db->query('SELECT `field_name` FROM `table_name`');
$query->data_seek(5); // Skip the first 5 rows
$row = $query->unbuffered_row();

Note

Not all database drivers support this feature and will return FALSE. Most notably – you won’t be able to use it with PDO.

Class Reference

classCI_DB_result
result([$type = ‘object’])
Parameters:
  • $type (string) – Type of requested results – array, object, or class name
Returns:

Array containing the fetched rows

Return type:

array

A wrapper for the result_array(), result_object() and custom_result_object() methods.

 

result_array()
Returns: Array containing the fetched rows
Return type: array

Returns the query results as an array of rows, where each row is itself an associative array.

 

result_object()
Returns: Array containing the fetched rows
Return type: array

Returns the query results as an array of rows, where each row is an object of type stdClass.

 

custom_result_object($class_name)
Parameters:
  • $class_name (string) – Class name for the resulting rows
Returns:

Array containing the fetched rows

Return type:

array

Returns the query results as an array of rows, where each row is an instance of the specified class.

row([$n = 0[, $type = ‘object’]])
Parameters:
  • $n (int) – Index of the query results row to be returned
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

The requested row or NULL if it doesn’t exist

Return type:

mixed

A wrapper for the row_array(), row_object() and ``custom_row_object() methods.

 

unbuffered_row([$type = ‘object’])
Parameters:
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

Next row from the result set or NULL if it doesn’t exist

Return type:

mixed

Fetches the next result row and returns it in the requested form.

 

row_array([$n = 0])
Parameters:
  • $n (int) – Index of the query results row to be returned
Returns:

The requested row or NULL if it doesn’t exist

Return type:

array

Returns the requested result row as an associative array.

 

row_object([$n = 0])
Parameters:
  • $n (int) – Index of the query results row to be returned
Returns:

The requested row or NULL if it doesn’t exist

Return type:

stdClass

Returns the requested result row as an object of type stdClass.

 

custom_row_object($n, $type)
Parameters:
  • $n (int) – Index of the results row to return
  • $class_name (string) – Class name for the resulting row
Returns:

The requested row or NULL if it doesn’t exist

Return type:

$type

Returns the requested result row as an instance of the requested class.

data_seek([$n = 0])
Parameters:
  • $n (int) – Index of the results row to be returned next
Returns:

TRUE on success, FALSE on failure

Return type:

bool

Moves the internal results row pointer to the desired offset.

 

set_row($key[, $value = NULL])
Parameters:
  • $key (mixed) – Column name or array of key/value pairs
  • $value (mixed) – Value to assign to the column, $key is a single field name
Return type:

void

Assigns a value to a particular column.

next_row([$type = ‘object’])
Parameters:
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

Next row of result set, or NULL if it doesn’t exist

Return type:

mixed

Returns the next row from the result set.

previous_row([$type = ‘object’])
Parameters:
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

Previous row of result set, or NULL if it doesn’t exist

Return type:

mixed

Returns the previous row from the result set.

first_row([$type = ‘object’])
Parameters:
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

First row of result set, or NULL if it doesn’t exist

Return type:

mixed

Returns the first row from the result set.

last_row([$type = ‘object’])
Parameters:
  • $type (string) – Type of the requested result – array, object, or class name
Returns:

Last row of result set, or NULL if it doesn’t exist

Return type:

mixed

Returns the last row from the result set.

num_rows()
Returns: Number of rows in the result set
Return type: int

Returns the number of rows in the result set.

 

num_fields()
Returns: Number of fields in the result set
Return type: int

Returns the number of fields in the result set.

 

field_data()
Returns: Array containing field meta-data
Return type: array

Generates an array of stdClass objects containing field meta-data.

free_result()
Return type: void

Frees a result set.

 

list_fields()
Returns: Array of column names
Return type: array

Returns an array containing the field names in the result set.

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