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PDO
PHP Manual

PDOStatement->fetch()

(PHP 5 >= 5.1.0, PECL pdo:0.1-1.0.3)

PDOStatement->fetch() — Fetches the next row from a result set

说明

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

Fetches a row from a result set associated with a PDOStatement object. The fetch_style parameter determines how PDO returns the row.

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 0-indexed 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->bindColumn() method

  • PDO::FETCH_CLASS: returns a new instance of the requested class, mapping the columns of the result set to named properties in the class. If fetch_style includes PDO::FETCH_CLASSTYPE (e.g. PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE) then the name of the class is determined from a value of the first column.

  • PDO::FETCH_INTO: updates an existing instance of the requested class, mapping the columns of the result set to named properties in the class

  • PDO::FETCH_LAZY: combines PDO::FETCH_BOTH and PDO::FETCH_OBJ, creating the object variable names as they are accessed

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

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

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. To request a scrollable cursor for your PDOStatement object, you must set the PDO::ATTR_CURSOR attribute to PDO::CURSOR_SCROLL when you prepare the SQL statement with PDO->prepare().

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.

返回值

The return value of this function on success depends on the fetch type. In all cases, FALSE is returned on failure.

范例

Example#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

Example#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
PHP Manual