The method of using preprocessing statements to obtain database query results in PHP varies from extension. 1. When using mysqli, you can obtain the associative array through get_result() and fetch_assoc(), which is suitable for modern environments; 2. You can also use bind_result() to bind variables, which is suitable for situations where there are few fields and fixed structures, and it is good compatibility but there are many fields when there are many fields; 3. When using PDO, you can obtain the associative array through fetch(PDO::FETCH_ASSOC), or use fetchAll() to obtain all data at once, with the interface unified and the error handling is clearer; in addition, you need to pay attention to parameter type matching, execution of execute(), timely release of resources, and enable error reports for debugging.
Prepared statements are a great way to prevent SQL injection and improve execution efficiency when using PHP to process database queries. How to get the result data after you execute a SELECT query with mysqli or PDO ? Here are a few key points from the perspective of practical operation.
Use mysqli to get the results of preprocessed statements
If you are using mysqli extension, there are two common ways to get the results of preprocessing statements: one is to cooperate with bind_result() , and the other is to use get_result() with fetch_assoc() and other functions.
Recommended practices are as follows:
$stmt = $conn->prepare("SELECT id, name FROM users WHERE age > ?");
$stmt->bind_param("i", $age);
$stmt->execute();
$result = $stmt->get_result(); // Key steps while ($row = $result->fetch_assoc()) {
echo $row['id'] . ' - ' . $row['name'] . '<br>';
}Note:
get_result()method requires MySQL Native Driver (mysqlnd). If the server does not support this method, you can consider usingbind_result()instead and usingfetch().
Use bind_result to bind variables directly
If you don't want to use get_result() , you can also bind variables through bind_result() , which is suitable for situations where there are fewer fields and fixed structures:
$stmt = $conn->prepare("SELECT id, name FROM users WHERE age > ?");
$stmt->bind_param("i", $age);
$stmt->execute();
$stmt->bind_result($id, $name); // Bind variable while ($stmt->fetch()) {
echo $id . ' - ' . $name . '<br>';
} This method does not require calling get_result() , and it is also suitable for older version environments.
- Advantages: Good compatibility
- Disadvantages: When there are many fields, it is troublesome to write and errors are prone to
More flexible with PDO to get results
If you are using PDO, the entire process will be more unified and support multiple results return methods:
$pdo = new PDO(...);
$stmt = $pdo->prepare("SELECT id, name FROM users WHERE age > ?");
$stmt->execute([$age]);
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
echo $row['id'] . ' - ' . $row['name'] . '<br>';
}-
fetch(PDO::FETCH_ASSOC)returns the associative array - You can also use
fetchAll()to get all data at once
The advantage of PDO is that the interface is unified and the error handling is clearer, which is suitable for modern PHP development projects.
Frequently Asked Questions and Precautions
- Pay attention to parameter type matching : When binding parameters, make sure the type is correct (i=integer, s=string, etc.)
- Don't forget to execute() : the prepared statement must be executed before the result can be obtained.
- Remember to close statements or release resources : Although PHP will recycle automatically, explicit closing is more standardized
- Turn on error report : convenient for debugging, especially quickly locate problems when execution fails
For example, enable error prompt:
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
Or in PDO:
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
Basically that's it. The way to obtain results through preprocessing statements in PHP is not complicated, but it is slightly different in terms of binding variables, obtaining data formats, etc., so you can choose the appropriate method according to the extension you use.
The above is the detailed content of PHP prepared statement get result. For more information, please follow other related articles on the PHP Chinese website!
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