(PHP 5, PHP 7)
mysqli_result::$lengths -- mysqli_fetch_lengths — Returns the lengths of the columns of the current row in the result set
面向对象风格
过程化风格
The mysqli_fetch_lengths() function returns an array containing the lengths of every column of the current row within the result set.
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.
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