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In PHP, the mysqli_stmt class is the core component used to execute prepared statements, while the attr_get function is used to obtain the properties of the preprocessed statement. With the evolution of PHP versions, especially from PHP 7 to PHP 8, the support and performance of the mysqli_stmt::attr_get function has also changed significantly. This article will analyze the differences between these two versions in detail in this function to help developers better understand and apply them.
mysqli_stmt::attr_get is a method of the mysqli_stmt class that gets the value of a given preprocessing statement attribute. The basic usage is as follows:
$stmt = $mysqli->prepare("SELECT * FROM users WHERE id = ?");
$attr_value = $stmt->attr_get(MYSQLI_STMT_ATTR_UPDATE_MAX_LENGTH);
This function accepts an attribute constant as a parameter and returns the corresponding attribute value.
In PHP 7, the mysqli_stmt::attr_get function has been introduced, and the supported properties are relatively limited. Commonly supported attributes include:
MYSQLI_STMT_ATTR_UPDATE_MAX_LENGTH
MYSQLI_STMT_ATTR_CURSOR_TYPE
MYSQLI_STMT_ATTR_PREFETCH_ROWS
MYSQLI_STMT_ATTR_PARAMS
However, PHP 7 does not support some new or extended properties, and some properties cannot be read through this function at all. In addition, the error handling mechanism is relatively simple. If an unsupported property is passed, false will usually be returned or a warning will be triggered.
Sample code:
$mysqli = new mysqli("m66.net", "user", "pass", "database");
$stmt = $mysqli->prepare("SELECT * FROM test WHERE id = ?");
if ($stmt) {
$attr = $stmt->attr_get(MYSQLI_STMT_ATTR_UPDATE_MAX_LENGTH);
var_dump($attr);
} else {
echo "Prepare failed: " . $mysqli->error;
}
PHP 8 has made several enhancements to mysqli_stmt::attr_get :
More attribute support
Support for more attributes is added in PHP 8, such as finer-grained cursor control and execution parameter information, and is compatible with the latest version of the MySQL client library.
Error handling is more stringent <br> When attr_get is called to pass unsupported attributes, PHP 8 throws a more explicit exception instead of just returning false or triggering a warning, which allows developers to locate issues faster
Performance optimization
PHP 8 optimizes the underlying C extension implementation, which improves the efficiency of property acquisition, especially in large batches of preprocessing statement operations.
Sample code:
$mysqli = new mysqli("m66.net", "user", "pass", "database");
$stmt = $mysqli->prepare("SELECT * FROM test WHERE id = ?");
if ($stmt) {
try {
$attr = $stmt->attr_get(MYSQLI_STMT_ATTR_UPDATE_MAX_LENGTH);
var_dump($attr);
} catch (mysqli_sql_exception $e) {
echo "Error: " . $e->getMessage();
}
} else {
echo "Prepare failed: " . $mysqli->error;
}
Version compatibility <br> If your project needs to be compatible with PHP 7 and PHP 8, it is recommended to detect the PHP version before calling attr_get and catch the exception to prevent unpredictable errors
Attribute constant confirmation <br> The attribute constants supported by different MySQL client versions and PHP versions are different. Be sure to check the official manual or dynamically check whether the attributes are valid at runtime.
Error and exception handling
PHP 8 improves exception handling mechanism, and code design should use try-catch blocks appropriately instead of relying on traditional error return values.
Overall, PHP 8 has made significant progress in the support of mysqli_stmt::attr_get function compared to PHP 7, mainly manifested in:
Supports more preprocessing statement properties;
stricter and clearer error and exception mechanisms;
Efficiency improvement brought by performance optimization.
Therefore, it is recommended that developers make full use of these improvements after upgrading to PHP 8 to improve code robustness and execution efficiency.
