mysqli_stmt::result_metadata

    mysqli_stmt_result_metadata

    (PHP 5, PHP 7, PHP 8)

    mysqli_stmt::result_metadata -- mysqli_stmt_result_metadata — Returns result set metadata from a prepared statement

    说明

    面向对象风格

    public mysqli_stmt::result_metadata(): mysqli_result|false

    过程化风格

    mysqli_stmt_result_metadata(mysqli_stmt $statement): mysqli_result|false

    If a statement passed to mysqli_prepare() is one that produces a result set, mysqli_stmt_result_metadata() returns the result object that can be used to process the meta information such as total number of fields and individual field information.

    注意:

    This result set pointer can be passed as an argument to any of the field-based functions that process result set metadata, such as:

    The result set structure should be freed when you are done with it, which you can do by passing it to mysqli_free_result()

    注意:

    The result set returned by mysqli_stmt_result_metadata() contains only metadata. It does not contain any row results. The rows are obtained by using the statement handle with mysqli_stmt_fetch().

    参数

    statement

    仅以过程化样式：由 mysqli_stmt_init() 返回的 mysqli_stmt 对象。

    返回值

    Returns a result object or false if an error occurred.

    错误／异常

    If mysqli error reporting is enabled (MYSQLI_REPORT_ERROR) and the requested operation fails, a warning is generated. If, in addition, the mode is set to MYSQLI_REPORT_STRICT, a mysqli_sql_exception is thrown instead.

    示例

    示例 #1 面向对象风格

    <?php
    $mysqli     = new mysqli("localhost", "my_user", "my_password", "test");

    $mysqli->query("DROP TABLE IF EXISTS friends");
    $mysqli->query("CREATE TABLE friends (id int, name varchar(20))");

    $mysqli->query("INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')");

    $stmt = $mysqli->prepare("SELECT id, name FROM friends");
    $stmt->execute();

    /* get resultset for metadata */
    $result = $stmt->result_metadata();

    /* retrieve field information from metadata result set */
    $field = $result->fetch_field();

    printf("Fieldname: %s\n", $field->name);

    /* close resultset */
    $result->close();

    /* close connection */
    $mysqli->close();
    ?>

    示例 #2 过程化风格

    <?php
    $link     = mysqli_connect("localhost", "my_user", "my_password", "test");

    mysqli_query($link, "DROP TABLE IF EXISTS friends");
    mysqli_query($link, "CREATE TABLE friends (id int, name varchar(20))");

    mysqli_query($link, "INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')");

    $stmt = mysqli_prepare($link, "SELECT id, name FROM friends");
    mysqli_stmt_execute($stmt);

    /* get resultset for metadata */
    $result = mysqli_stmt_result_metadata($stmt);

    /* retrieve field information from metadata result set */
    $field = mysqli_fetch_field($result);

    printf("Fieldname: %s\n", $field->name);

    /* close resultset */
    mysqli_free_result($result);

    /* close connection */
    mysqli_close($link);
    ?>

    参见

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    用户贡献的备注 1 note

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    potherca at gmail dot com
    14 years ago
    If result_metadata() returns false but error/errno/sqlstate tells you no error occurred, this means your query is one that does not produce a result set, i.e. an INSERT/UPDATE/DELETE query instead of a SELECT query.

    This is stated in the documentation where it says "If a statement passed to mysqli_prepare() is one that produces a result set, mysqli_stmt_result_metadata() returns the result object", but it might not be clear to everyone what this entails exactly.

    Hope this helps.
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