Database operation to obtain a single result: use mysqli to connect to the database

Question

This is my first time trying to use mySQLi. In the case of a loop, I've done this. The results of the loop show up, but when I try to show a single record it gets stuck. Here is the working loop code.

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

$conn = mysqli_connect($hostname, $username, $password, $database);
?>

<?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 the records*/
for($i=0; $i<$num_results; $i ) {
$row = mysqli_fetch_assoc($result);
?>

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

<?php
// end loop
}
?>

How do I display a single record, any record, name or email, from the first row or anywhere else, just a single record, how do I do this? In case of single record, consider removing the above loop part and let us display any single record without using loop.

Answer 1

Use mysqli_fetch_row(). Try the following code:

$query = "SELECT ssfullname, ssemail FROM userss WHERE user_id = ".$user_id;
$result = mysqli_query($conn, $query);
$row   = mysqli_fetch_row($result);

$ssfullname = $row['ssfullname'];
$ssemail    = $row['ssemail'];

Answer 2

When only one result is needed, there is no need to use a loop. Get the row directly.

• If you need to obtain the entire row of data as an associative array:

  $row = $result->fetch_assoc();

• If only one value is required, starting with PHP 8.2:

  $value = $result->fetch_column();

• Or for older versions:

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

Here are complete examples of different use cases

Variables used in queries

When variables need to be used in a query, preprocessing statements must be used. For example, let's say we have a variable $id:

PHP >= 8.2

// 获取单行
$sql = "SELECT fullname, email FROM users WHERE id=?";
$row = $conn->execute_query($query, [$id])->fetch_assoc();

// 如果只需要一个值
$sql = "SELECT count(*) FROM users WHERE id=?";
$count = $conn->execute_query($query, [$id])->fetch_column();

Older versions of PHP:

// 获取单行
$query = "SELECT fullname, email FROM users WHERE id=?";
$stmt = $conn->prepare($query);
$stmt->bind_param("s", $id);
$stmt->execute();
$result = $stmt->get_result();
$row = $result->fetch_assoc();

// 如果只需要一个值
$query = "SELECT count(*) FROM userss WHERE id=?";
$stmt = $conn->prepare($query);
$stmt->bind_param("s", $id);
$stmt->execute();
$result = $stmt->get_result();
$count = $result->fetch_row()[0] ?? false;

A detailed explanation of the above process can be found in my article . The reason why this procedure must be followed is explained in this famous Question.

There are no variables in the query

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

$query = "SELECT fullname, email FROM users ORDER BY ssid";
$result = $conn->query($query);
// 如果需要一个数组
$row = $result->fetch_assoc();
// 或者如果只需要一个值
$value = $result->fetch_row()[0] ?? false;