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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]]] )

警告
本函数是实验性的。本函数的行为，包括函数名称以及其它任何关于本函数的文档可能会在没有通知的情况下随 PHP 以后的发布而改变。使用本函数风险自担。

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.

## 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::fetchSingle()
PDOStatement::prepare()
PDOStatement::setFetchMode()

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