PHP 教程
PDOStatement::fetch
PHP PDO 參考手冊PDOStatement::fetch — 從結(jié)果集中獲取下一行(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0)
說明
語法
mixed PDOStatement::fetch ([ int $fetch_style [, int $cursor_orientation = PDO::FETCH_ORI_NEXT [, int $cursor_offset = 0 ]]] )
從一個 PDOStatement 對象相關(guān)的結(jié)果集中獲取下一行。fetch_style 參數(shù)決定 POD 如何返回行。
參數(shù)
fetch_style
控制下一行如何返回給調(diào)用者。此值必須是 PDO::FETCH_* 系列常量中的一個，默認為 PDO::ATTR_DEFAULT_FETCH_MODE 的值 （默認為 PDO::FETCH_BOTH ）。
PDO::FETCH_ASSOC：返回一個索引為結(jié)果集列名的數(shù)組
PDO::FETCH_BOTH（默認）：返回一個索引為結(jié)果集列名和以0開始的列號的數(shù)組
PDO::FETCH_BOUND：返回
TRUE，并分配結(jié)果集中的列值給PDOStatement::bindColumn() 方法綁定的 PHP 變量。PDO::FETCH_CLASS：返回一個請求類的新實例，映射結(jié)果集中的列名到類中對應(yīng)的屬性名。如果
fetch_style包含 PDO::FETCH_CLASSTYPE（例如：PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE），則類名由第一列的值決定PDO::FETCH_INTO：更新一個被請求類已存在的實例，映射結(jié)果集中的列到類中命名的屬性
PDO::FETCH_LAZY：結(jié)合使用 PDO::FETCH_BOTH 和 PDO::FETCH_OBJ，創(chuàng)建供用來訪問的對象變量名
PDO::FETCH_NUM：返回一個索引為以0開始的結(jié)果集列號的數(shù)組
PDO::FETCH_OBJ：返回一個屬性名對應(yīng)結(jié)果集列名的匿名對象
cursor_orientation
對于 一個 PDOStatement 對象表示的可滾動游標，該值決定了哪一行將被返回給調(diào)用者。此值必須是 PDO::FETCH_ORI_* 系列常量中的一個，默認為 PDO::FETCH_ORI_NEXT。要想讓 PDOStatement 對象使用可滾動游標，必須在用 PDO::prepare() 預(yù)處理SQL語句時，設(shè)置 PDO::ATTR_CURSOR 屬性為 PDO::CURSOR_SCROLL。
offset
對于一個 cursor_orientation 參數(shù)設(shè)置為 PDO::FETCH_ORI_ABS 的PDOStatement 對象代表的可滾動游標，此值指定結(jié)果集中想要獲取行的絕對行號。
對于一個 cursor_orientation 參數(shù)設(shè)置為 PDO::FETCH_ORI_REL 的PDOStatement 對象代表的可滾動游標，此值指定想要獲取行相對于調(diào)用 PDOStatement::fetch() 前游標的位置
返回值
此函數(shù)（方法）成功時返回的值依賴于提取類型。在所有情況下，失敗都返回 FALSE 。
實例
用不同的提取方式獲取行
<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
/* 運用 PDOStatement::fetch 風格 */
print("PDO::FETCH_ASSOC: ");
print("Return next row as an array indexed by column namen");
$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 numbern");
$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 propertiesn");
$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 propertiesn");
$result = $sth->fetch(PDO::FETCH_OBJ);
print $result->NAME;
print("n");
?>
以上實例會輸出：
PDO::FETCH_ASSOC: Return next row as an array indexed by column name
Array
(
[NAME] => apple
[COLOUR] => red
)
PDO::FETCH_BOTH: Return next row as an array indexed by both column name and number
Array
(
[NAME] => banana
[0] => banana
[COLOUR] => yellow
[1] => yellow
)
PDO::FETCH_LAZY: Return next row as an anonymous object with column names as properties
PDORow Object
(
[NAME] => orange
[COLOUR] => orange
)
PDO::FETCH_OBJ: Return next row as an anonymous object with column names as properties
kiwi
使用一個可滾動游標獲取行
<?php
function readDataForwards($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);
?>
以上實例會輸出：
Reading forwards: 21 10 5 16 0 5 19 20 10 Reading backwards: 19 20 10 16 0 5 21 10 5
其他擴展