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PHP - Manual: mysqli_result::$lengths

2024-12-23

mysqli_result::$lengths

mysqli_fetch_lengths

(PHP 5, PHP 7, PHP 8)

mysqli_result::$lengths -- mysqli_fetch_lengthsReturns the lengths of the columns of the current row in the result set

说明

面向对象风格

过程化风格

mysqli_fetch_lengths(mysqli_result $result): array|false

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()mysqli_use_result()mysqli_stmt_get_result() 返回的 mysqli_result 对象。

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

示例 #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();
?>

示例 #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
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官方地址:https://www.php.net/manual/en/mysqli-result.lengths.php

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