mysqli_result::$lengths()

(PHP 5, PHP 7)

Returns the lengths of the columns of the current row in the result set

说明

面向对象风格
array $mysqli_result->lengths;

过程化风格
mysqli_fetch_lengths(mysqli_result$result): array

The mysqli_fetch_lengths() function returns an array containing the lengths of every column of the current row within the result set.

参数

$result

仅以过程化样式：由mysqli_query()，mysqli_store_result()或mysqli_use_result()返回的结果集标识。

返回值

An array of integers representing the size of each column(not including any terminating null characters).FALSE if an error occurred.

mysqli_fetch_lengths() is valid only for the current row of the result set. It returns FALSE if you call it before calling mysqli_fetch_row/array/object or after retrieving all rows in the result.

范例

Example #1 面向对象风格

<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
$query = "SELECT * from Country ORDER BY Code LIMIT 1";
if ($result = $mysqli->query($query)) {
    $row = $result->fetch_row();
    /* display column lengths */
    foreach ($result->lengths as $i => $val) {
        printf("Field %2d has Length %2d\n", $i+1, $val);
    }
    $result->close();
}
/* close connection */
$mysqli->close();
?>

Example #2 过程化风格

<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}
$query = "SELECT * from Country ORDER BY Code LIMIT 1";
if ($result = mysqli_query($link, $query)) {
    $row = mysqli_fetch_row($result);
    /* display column lengths */
    foreach (mysqli_fetch_lengths($result) as $i => $val) {
        printf("Field %2d has Length %2d\n", $i+1, $val);
    }
    mysqli_free_result($result);
}
/* close connection */
mysqli_close($link);
?>

以上例程会输出：

Field  1 has Length  3
Field  2 has Length  5
Field  3 has Length 13
Field  4 has Length  9
Field  5 has Length  6
Field  6 has Length  1
Field  7 has Length  6
Field  8 has Length  4
Field  9 has Length  6
Field 10 has Length  6
Field 11 has Length  5
Field 12 has Length 44
Field 13 has Length  7
Field 14 has Length  3
Field 15 has Length  2