PDOStatement::fetch · W3School PHP 参考手册

# PDOStatement::fetch PDOStatement::fetch — 从结果集中获取下一行(PHP 5 >= 5.1.0, PECL pdo >= 0.1.0) ## 说明 ### 语法 ``` mixed PDOStatement::fetch ([ int $fetch_style [, int $cursor_orientation = PDO::FETCH_ORI_NEXT [, int $cursor_offset = 0 ]]] ) ``` 从一个 PDOStatement 对象相关的结果集中获取下一行。fetch_style 参数决定 POD 如何返回行。 ## 参数 **fetch_style** 控制下一行如何返回给调用者。此值必须是 PDO::FETCH_* 系列常量中的一个，缺省为 PDO::ATTR_DEFAULT_FETCH_MODE 的值（默认为 PDO::FETCH_BOTH ）。 * _PDO::FETCH_ASSOC_：返回一个索引为结果集列名的数组 * _PDO::FETCH_BOTH_（默认）：返回一个索引为结果集列名和以0开始的列号的数组 * _PDO::FETCH_BOUND_：返回 **`TRUE`** ，并分配结果集中的列值给PDOStatement::bindColumn() 方法绑定的 PHP 变量。 * _PDO::FETCH_CLASS_：返回一个请求类的新实例，映射结果集中的列名到类中对应的属性名。如果 `fetch_style` 包含 PDO::FETCH_CLASSTYPE（例如：_PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE_），则类名由第一列的值决定 * _PDO::FETCH_INTO_：更新一个被请求类已存在的实例，映射结果集中的列到类中命名的属性 * _PDO::FETCH_LAZY_：结合使用 _PDO::FETCH_BOTH_ 和 _PDO::FETCH_OBJ_，创建供用来访问的对象变量名 * _PDO::FETCH_NUM_：返回一个索引为以0开始的结果集列号的数组 * _PDO::FETCH_OBJ_：返回一个属性名对应结果集列名的匿名对象 **cursor_orientation** 对于一个 PDOStatement 对象表示的可滚动游标，该值决定了哪一行将被返回给调用者。此值必须是 PDO::FETCH_ORI_* 系列常量中的一个，默认为 PDO::FETCH_ORI_NEXT。要想让 PDOStatement 对象使用可滚动游标，必须在用 PDO::prepare() 预处理SQL语句时，设置 PDO::ATTR_CURSOR 属性为 PDO::CURSOR_SCROLL。 **offset** 对于一个 cursor_orientation 参数设置为 PDO::FETCH_ORI_ABS 的PDOStatement 对象代表的可滚动游标，此值指定结果集中想要获取行的绝对行号。对于一个 cursor_orientation 参数设置为 PDO::FETCH_ORI_REL 的PDOStatement 对象代表的可滚动游标，此值指定想要获取行相对于调用 PDOStatement::fetch() 前游标的位置 ## 返回值此函数（方法）成功时返回的值依赖于提取类型。在所有情况下，失败都返回 FALSE 。 ## 实例 ### 用不同的提取方式获取行 ``` <?php $sth = $dbh->prepare("SELECT name, colour FROM fruit"); $sth->execute(); /* 运用 PDOStatement::fetch 风格 */ 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 $result->NAME; print("\n"); ?> ``` 以上实例会输出： ``` PDO::FETCH_ASSOC: Return next row as an array indexed by column name Array ( [NAME] => apple [COLOUR] => red ) PDO::FETCH_BOTH: Return next row as an array indexed by both column name and number Array ( [NAME] => banana [0] => banana [COLOUR] => yellow [1] => yellow ) PDO::FETCH_LAZY: Return next row as an anonymous object with column names as properties PDORow Object ( [NAME] => orange [COLOUR] => orange ) PDO::FETCH_OBJ: Return next row as an anonymous object with column names as properties kiwi ``` ### 使用一个可滚动游标获取行 ``` <?php function readDataForwards($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); ?> ``` 以上实例会输出： ``` Reading forwards: 21 10 5 16 0 5 19 20 10 Reading backwards: 19 20 10 16 0 5 21 10 5 ```