php query database sorting

PHP is a well-known and popular server-side programming language. It is very powerful and allows developers to quickly develop Web applications. Therefore, PHP is crucial for web developers. Among them, querying and sorting are one of the most important functions in PHP. They can make data more orderly and easier to manage. In this article, we will explore how to query and sort a database using PHP.

1. Establish a database connection

Before querying and sorting data, you need to establish a connection with the database and provide necessary information, such as user name, password, etc. In PHP, to establish a connection, we need to use the mysqli_connect() function.

For example:

`
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = “mydb”;

//Establish a connection
$conn = mysqli_connect($servername, $username, $password, $dbname);

//Check whether the connection is successful
if (!$conn) {

die("连接失败: " . mysqli_connect_error());

}
`

2. Query the database

After the connection is established, we can start querying the database. For simple queries, we can use the mysqli_query() function. For example, if we take the "users" table as an example, we can use the following statement to query the information of all users:

`
$query = "SELECT * FROM users";
$result = mysqli_query( $conn, $query);
`

This will return the following results:

##idnameemailphone1John Doe john@example.com555-12342Jane Doejane@example .com555-56783Bob Smithbob@example.com555 -9012

`

`

3. Sorting data

In order to make the data more orderly and manageable, we need to sort it . In PHP, we can use ORDER BY statement for sorting. For example, if we want to sort the data in the "users" table in ascending order according to the "name" column, we can use the following statement:

`

$query = "SELECT * FROM users ORDER BY name ASC" ;
$result = mysqli_query($conn, $query);
`

This will return the following results:

`idnameemailphone 2Jane Doejane@example.com555-56781John Doe john@example.com555-12343Bob Smithbob@example .com555-9012`

Similarly, if we want to compare the users in the "users" table according to the "id" column To sort the data in descending order, you can use the following statement:

`

$query = “SELECT * FROM users ORDER BY id DESC”;
$result = mysqli_query($conn, $query);
`

This will return the following results:

`id nameemailphone3Bob Smithbob@ example.com555-90122Jane Doejane@example.com 555-56781John Doejohn@example.com555-1234`

4. Complete code example

The complete PHP code example is as follows:

`

$servername = "localhost ”;
$username = “username”;
$password = “password”;
$dbname = “mydb”;

// Establish a connection

$conn = mysqli_connect( $servername, $username, $password, $dbname);

// Check whether the connection is successful

if (!$conn) {

die("连接失败: " . mysqli_connect_error());

}

/ / Query and sort data

$query = “SELECT * FROM users ORDER BY name ASC”;
$result = mysqli_query($conn, $query);

//Output data

if (mysqli_num_rows($result) > 0) {

while($row = mysqli_fetch_assoc($result)) {
    echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. " - Phone: " . $row["phone"]. "<br>";
}

} else {

echo "0 结果";

}

mysqli_close($conn);

`

The above code will output the following results:

`

id: 2 - Name: Jane Doe - Email: jane@example.com - Phone: 555-5678
id: 1 - Name: John Doe - Email: john@example.com - Phone: 555-1234
id: 3 - Name: Bob Smith - Email: bob@example.com - Phone: 555-9012
`

Summary

In this article, we learned how to perform database queries and sorting in PHP. First, we establish a connection to the database and then use the mysqli_query() function to query. Finally, use the ORDER BY statement to sort the results for better data management. This will make our application more reliable and easier to maintain.

Using PHP to query and sort the database is one of the skills that developers must master. When we are able to combine these features, we are able to create more efficient and intelligent web applications.

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