PDO::setAttribute
(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo >= 0.1.0)
PDO::setAttribute — 设置属性
说明
设置数据库句柄属性。下面列出了一些可用的通用属性；有些驱动可能使用另外的特定属性。 请注意，特定的驱动程序属性不得用于其他驱动程序。
PDO::ATTR_CASE-
强制列名为指定的大小写。可以采用以下某个值：
PDO::CASE_LOWER- 强制列名小写。
PDO::CASE_NATURAL- 保留数据库驱动返回的列名。
PDO::CASE_UPPER- 强制列名大写。
PDO::ATTR_ERRMODE-
PDO 的报错方式。可以采用以下某个值：
PDO::ERRMODE_SILENT- 仅设置错误代码。
PDO::ERRMODE_WARNING-
引发
E_WARNING警告。 PDO::ERRMODE_EXCEPTION- 抛出 PDOException。
PDO::ATTR_ORACLE_NULLS-
注意: 此属性适用于所有驱动程序，而不仅仅是 Oracle。
确定是否以及如何转换
null和空字符串。可以采用以下值之一：PDO::NULL_NATURAL- 不发生转换。
PDO::NULL_EMPTY_STRING-
空字符串转换为
null。 PDO::NULL_TO_STRING-
null被转换为空字符串。
PDO::ATTR_STRINGIFY_FETCHES-
控制是否将获取的值（
null除外）转换为字符串。采用 bool 类型的值：true表示启用，false表示禁用（默认）。除非将PDO::ATTR_ORACLE_NULLS设置为PDO::NULL_TO_STRING，否则null值保持不变。 PDO::ATTR_STATEMENT_CLASS-
设置从 PDOStatement 派生的用户提供的语句类。 需要
array(string classname, array(mixed constructor_args))。警告不能用于持久 PDO 实例。
PDO::ATTR_TIMEOUT-
指定超时的秒数。需要 int 类型的值。
注意:
并非所有驱动都支持此选项，这意味着驱动和驱动之间可能会有差异。比如，SQLite 等待的时间达到此值后就放弃获取可写锁，但其他驱动可能会将此值解释为一个连接或读取超时的间隔。
PDO::ATTR_AUTOCOMMIT-
注意: 仅适用于 OCI、Firebird 和 MySQL 驱动程序。
PDO::ATTR_EMULATE_PREPARES-
注意: 仅适用于 OCI、Firebird 和 MySQL 驱动程序。
是否启用或禁用预处理语句的模拟。有些驱动天然不支持或有限度地支持预处理语句。如果设置为
true，PDO 始终模拟预处理语句，否则 PDO 将会尝试使用本地预处理语句。如果驱动不能成功预处理当前查询，PDO 将始终回退到模拟预处理语句上。 PDO::MYSQL_ATTR_USE_BUFFERED_QUERY-
注意: 仅适用于 MySQL 驱动程序。
PDO::ATTR_DEFAULT_FETCH_MODE-
设置默认获取模式。关于模式的说明以及如何使用可以在 PDOStatement::fetch() 文档找到。
参数
attribute-
要修改的属性。
value-
设置
attribute的值，属性的不同导致需要的类型也会不同。
参见
- PDO::getAttribute() - 取回一个数据库连接的属性
- PDOStatement::getAttribute() - 检索语句属性
- PDOStatement::setAttribute() - 设置一个语句属性
用户贡献的备注 8 notes
Because no examples are provided, and to alleviate any confusion as a result, the setAttribute() method is invoked like so:
setAttribute(ATTRIBUTE, OPTION);
So, if I wanted to ensure that the column names returned from a query were returned in the case the database driver returned them (rather than having them returned in all upper case [as is the default on some of the PDO extensions]), I would do the following:
<?php
// Create a new database connection.
$dbConnection = new PDO($dsn, $user, $pass);
// Set the case in which to return column_names.
$dbConnection->setAttribute(PDO::ATTR_CASE, PDO::CASE_NATURAL);
?>
Hope this helps some of you who learn by example (as is the case with me).
.ColinThis is an update to a note I wrote earlier concerning how to set multiple attributes when you create you PDO connection string.
You can put all the attributes you want in an associative array and pass that array as the fourth parameter in your connection string. So it goes like this:
<?php
$options = [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_CASE => PDO::CASE_NATURAL,
PDO::ATTR_ORACLE_NULLS => PDO::NULL_EMPTY_STRING
];
// Now you create your connection string
try {
// Then pass the options as the last parameter in the connection string
$connection = new PDO("mysql:host=$host; dbname=$dbname", $user, $password, $options);
// That's how you can set multiple attributes
} catch(PDOException $e) {
die("Database connection failed: " . $e->getMessage());
}
?>It is worth noting that not all attributes may be settable via setAttribute(). For example, PDO::MYSQL_ATTR_MAX_BUFFER_SIZE is only settable in PDO::__construct(). You must pass PDO::MYSQL_ATTR_MAX_BUFFER_SIZE as part of the optional 4th parameter to the constructor. This is detailed in http://bugs.php.net/bug.php?id=38015Well, I have not seen it mentioned anywhere and thought its worth mentioning. It might help someone. If you are wondering whether you can set multiple attributes then the answer is yes.
You can do it like this:
try {
$connection = new PDO("mysql:host=$host; dbname=$dbname", $user, $password);
// You can begin setting all the attributes you want.
$connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$connection->setAttribute(PDO::ATTR_CASE, PDO::CASE_NATURAL);
$connection->setAttribute(PDO::ATTR_ORACLE_NULLS, PDO::NULL_EMPTY_STRING);
// That's how you can set multiple attributes
}
catch(PDOException $e)
{
die("Database connection failed: " . $e->getMessage());
}
I hope this helps somebody. :)Note that contrary to most PDO methods, setAttribute does not throw a PDOException when it returns false.For PDO::ATTR_EMULATE_PREPARES, the manual states a boolean value is required. However, when getAttribute() is used to check this value, an integer (1 or 0) is returned rather than true or false.
This means that if you are checking a PDO object is configured as required then
<?php
// Check emulate prepares is off
if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) !== false) {
/* do something */
}
?>
will always 'do something', regardless.
Either
<?php
// Check emulate prepares is off
if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) != false) {
/* do something */
}
?>
or
<?php
// Check emulate prepares is off
if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) !== 0) {
/* do something */
}
?>
is needed instead.
Also worth noting that setAttribute() does, in fact, accept an integer value if you want to be consistent.There is also a way to specifie the default fetch mode :
<?php
$connection = new PDO($connection_string);
$connection->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);
?>Note that in order for
\PDO::ATTR_TIMEOUT
to have any effect, you must set
\PDO::ATTR_ERRMODE=>\PDO::ERRMODE_EXCEPTION.
If
\PDO::ATTR_ERRMODE=>\PDO::ERRMODE_WARNING
it doesn't appear to do anything.