Generating Query Results¶
There are several ways to generate 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().
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 $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 = $this->db->query("YOUR QUERY");
if ($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; // 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 = $this->db->query("YOUR QUERY");
if ($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’)
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
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.