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PDOStatement::fetch

(no version information, might be only in CVS)

PDOStatement::fetch --  Fetches the next row from a result set

说明

mixed PDOStatement::fetch ( [int fetch_style [, int cursor_orientation [, int cursor_offset]]] )

Fetches a row from a result set associated with a PDOStatement object.

参数

fetch_style

Controls how the next row will be returned to the caller. This value must be one of the PDO_FETCH_* constants, defaulting to PDO_FETCH_BOTH.

  • PDO_FETCH_ASSOC: returns an array indexed by column name as returned in your result set

  • PDO_FETCH_BOTH (default): returns an array indexed by both column name and column number as returned in your result set

  • PDO_FETCH_BOUND: returns TRUE and assigns the values of the columns in your result set to the PHP variables to which they were bound with the PDOStatement::bindParam() method

  • PDO_FETCH_LAZY: combines PDO_FETCH_BOTH and PDO_FETCH_OBJ, creating the object variable names as they are accessed

  • PDO_FETCH_OBJ: returns an anonymous object with property names that correspond to the column names returned in your result set

  • PDO_FETCH_NUM: returns an array indexed by column number as returned in your result set, starting at column 0

cursor_orientation

For a PDOStatement object representing a scrollable cursor, this value determines which row will be returned to the caller. This value must be one of the PDO_FETCH_ORI_* constants, defaulting to PDO_FETCH_ORI_NEXT.

offset

For a PDOStatement object representing a scrollable cursor for which the cursor_orientation parameter is set to PDO_FETCH_ORI_ABS, this value specifies the absolute number of the row in the result set that shall be fetched.

For a PDOStatement object representing a scrollable cursor for which the cursor_orientation parameter is set to PDO_FETCH_ORI_REL, this value specifies the row to fetch relative to the cursor position before PDOStatement::fetch() was called.

范例

例子 1. Fetching rows using different fetch styles

<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();

/* Exercise PDOStatement::fetch styles */
print("PDO_FETCH_ASSOC: ");
print("Return next row as an array indexed by column name\n");
$result = $sth->fetch(PDO_FETCH_ASSOC);
print_r($result);
print("\n");

print("PDO_FETCH_BOTH: ");
print("Return next row as an array indexed by both column name and number\n");
$result = $sth->fetch(PDO_FETCH_BOTH);
print_r($result);
print("\n");

print("PDO_FETCH_LAZY: ");
print("Return next row as an anonymous object with column names as properties\n");
$result = $sth->fetch(PDO_FETCH_LAZY);
print_r($result);
print("\n");

print("PDO_FETCH_OBJ: ");
print("Return next row as an anonymous object with column names as properties\n");
$result = $sth->fetch(PDO_FETCH_OBJ);
print $result->NAME;
print("\n");
?>

上例将输出：

PDO_FETCH_ASSOC: Return next row as an array indexed by column name
Array
(
    [NAME] => apple
    [COLOUR] => red
)

PDO_FETCH_BOTH: Return next row as an array indexed by both column name and number
Array
(
    [NAME] => banana
    [0] => banana
    [COLOUR] => yellow
    [1] => yellow
)

PDO_FETCH_LAZY: Return next row as an anonymous object with column names as properties
PDORow Object
(
    [NAME] => orange
    [COLOUR] => orange
)

PDO_FETCH_OBJ: Return next row as an anonymous object with column names as properties
kiwi

例子 2. Fetching rows with a scrollable cursor

<?php
function readDataForwards($dbh) {
  $sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY BET';
  try {
    $stmt = $dbh->prepare($sql, array(PDO_ATTR_CURSOR, PDO_CURSOR_SCROLL));
    $stmt->execute();
    while ($row = $stmt->fetch(PDO_FETCH_NUM, PDO_FETCH_ORI_NEXT)) {
      $data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
      print $data;
    }
    $stmt = null;
  }
  catch (PDOException $e) {
    print $e->getMessage();
  }
}
function readDataBackwards($dbh) {
  $sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY bet';
  try {
    $stmt = $dbh->prepare($sql, array(PDO_ATTR_CURSOR, PDO_CURSOR_SCROLL));
    $stmt->execute();
    $row = $stmt->fetch(PDO_FETCH_NUM, PDO_FETCH_ORI_LAST);
    do {
      $data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
      print $data;
    } while ($row = $stmt->fetch(PDO_FETCH_NUM, PDO_FETCH_ORI_PRIOR));
    $stmt = null;
  }
  catch (PDOException $e) {
    print $e->getMessage();
  }
}

print "Reading forwards:\n";
readDataForwards($conn);

print "Reading backwards:\n";
readDataBackwards($conn);
?>

上例将输出：

Reading forwards:
21    10    5
16    0     5
19    20    10

Reading backwards:
19    20    10
16    0     5
21    10    5

参见

PDO::query()
PDOStatement::fetchAll()
PDOStatement::fetchColumn()
PDOStatement::prepare()
PDOStatement::setFetchMode()


add a note add a note User Contributed Notes
terry at bitsoup dot com
03-Mar-2006 04:46
WARNING:
fetch() does NOT adhere to SQL-92 SQLSTATE standard when dealing with empty datasets.

Instead of setting the errorcode class to 20 to indicate "no data found", it returns a class of 00 indicating success, and returns NULL to the caller.

This also prevents the exception mechainsm from firing.

Programmers will need to explicitly code tests for empty resultsets after any fetch*() instead of relying on the default behavior of the RDBMS.

I tried logging this as a bug, but it was dismissed as "working as intended". Just a head's up.
avinoamr at gmail dot com
20-Jan-2006 06:48
Note that using the FETCH_CLASS mechanism does NOT trigger the class's constructor! You must explicity instantiate the class to use it's constructor behavior.
fh at ez dot no
25-Nov-2005 04:13
I can also add that the constructor is run _after_ the data is set on the object if yo use PDO::FETCH_CLASS.
fh at ez dot no
25-Nov-2005 03:58
If you want to use PDO::FETCH_CLASS you need to set it up with setFetchMode first like so:
       $stmt->setFetchMode( PDO::FETCH_CLASS, 'classType', array( 'parameters to constructor' );
       $object = $stmt->fetch( PDO::FETCH_CLASS );
If you ommit this PHP will segfault.
aledmb at gmail dot com
22-Oct-2005 01:22
note that fetch constants are not included in the PDO class for PHP versions prior to 5.1
add a note add a note


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