Generating Query Results
************************

There are several ways to generate query results:

* Result Arrays

* Result Rows

* Custom Result Objects

* Result Helper Methods

* Class Reference


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
===============

class CI_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.

      Usage: see Result Arrays.

   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.

      Usage: see Result Arrays.

   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".

      Usage: see Result Arrays.

   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.

      Usage: see Result Rows.

   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.

      Usage: see Result Rows.

   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.

      Usage: see Result Rows.

   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".

      Usage: see Result Rows.

   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.

      Usage: see Result Helper Methods.

   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.

      Usage: see Result Helper Methods.

   num_fields()

      Returns:
         Number of fields in the result set

      Return type:
         "int"

      Returns the number of fields in the result set.

      Usage: see Result Helper Methods.

   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.

      Usage: see Result Helper Methods.

   list_fields()

      Returns:
         Array of column names

      Return type:
         "array"

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