使用mySQLi从数据库获得单个结果 [英] Single Result from Database by using mySQLi

问题描述

我正在尝试首次使用mySQLi.我已经完成了以防万一.循环结果正在显示，但是当我尝试显示单个记录时我被卡住了.这是有效的循环代码.

I am trying to use mySQLi for the first time. I have done it in case of loop. Loop results are showing but i am stuck when i try to show single record. Here is loop code that is working.

<?php
// Connect To DB
$hostname="localhost";
$database="mydbname";
$username="root";
$password="";

@$conn = mysqli_connect($hostname, $username, $password)
        or die("Could not connect to server " . mysql_error()); 
    mysqli_select_db($conn, $database)
        or die("Error: Could not connect to the database: " . mysql_error());

    /*Check for Connection*/
    if(mysqli_connect_errno()){
        // Display Error message if fails
        echo 'Error, could not connect to the database please try again again.';
    exit();
    }
?>

<?php
$query = "SELECT ssfullname, ssemail FROM userss ORDER BY ssid";
$result = mysqli_query($conn, $query);
@$num_results = mysqli_num_rows($result);
?>

<?php
/*Loop through each row and display records */
for($i=0; $i<$num_results; $i++) {
$row = mysqli_fetch_assoc($result);
?>

<?php // echo 'Name' .$row['ssfullname'] . 'email' . $row['ssemail'] . "\n"; ?>

Name: <?php print $row['ssfullname']; ?>
<br />
Email: <?php print $row['ssemail']; ?>
<br /><br />

<?php 
// end loop
} 
?>

上面的代码在循环的情况下很好. 现在如何显示第一行或任何记录中的任何记录，任何记录，名称或电子邮件，仅显示单个记录，我将如何处理? 在单个记录的情况下，请考虑删除所有上述循环部分，并显示没有循环的任何单个记录.

Above code is fine in case of loop. Now how do i show single record, any record, name or email, from first row or whatever, just single record, how would i do that? In single record case, consider all above loop part removed and lets show any single record without loop.

推荐答案

当仅需要单个结果时，则不应使用循环.只需立即获取该行.

When just a single result is needed, then no loop should be used. Just fetch the row right away.

• 如果需要将整行提取到关联数组中:

• In case you need to fetch the entire row into associative array:

$row = $result->fetch_assoc();

如果您只需要一个值

in case you need just a single value

$row = $result->fetch_row();
$value = $row[0];

以下是针对不同用例的完整示例

Below are complete examples for different use cases

在查询中使用变量时，必须使用准备好的语句.例如，假设我们有一个变量$id:

When variables are to be used in the query, then a prepared statement must be used. For example, given we have a variable $id:

$query = "SELECT ssfullname, ssemail FROM userss WHERE ud=?";
$stmt = $conn->prepare($query);
$stmt->bind_param("s", $id);
$stmt->execute()
$result = $stmt->get_result();
// in case you need an array
$row = $result->fetch_assoc();
// OR in case you need just a single value
$row = $result->fetch_row();
$value = $row[0];

可以在我的文章中找到上述过程的详细说明.关于为什么必须遵循此问题的解释，请参见此著名的问题

The detailed explanation of the above process can be found in my article. As to why you must follow it is explained in this famous question

在您的情况下，如果查询中不使用任何变量，则可以使用query()方法:

In your case, where no variables to be used in the query, you can use the query() method:

$query = "SELECT ssfullname, ssemail FROM userss ORDER BY ssid";
$result = $conn->($query);
// in case you need an array
$row = $result->fetch_assoc();
// OR in case you need just a single value
$row = $result->fetch_row();
$value = $row[0];

顺便说一句，尽管在学习没问题的情况下使用原始API，但将来还是可以考虑使用一些数据库抽象库.
它将全部您的数据库代码分成三行:

By the way, although using raw API while learning is okay, consider using some database abstraction library in the future.
It will turn all your database code into 3 lines:

include 'database.class.php';
$db  = new DB();
$row = $db->getRow("SELECT ssfullname, ssemail FROM userss ORDER BY ssid LIMIT 1");

这篇关于使用mySQLi从数据库获得单个结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！