How to query SQL using PHP and convert it to an array

In web development, converting data queried from the database into array format is a very common operation. When using PHP for web development, querying SQL and converting it into an array is also a very important skill. This article will introduce how to use PHP to query SQL and convert it into an array.

1. Connect to the database

Before using PHP to query SQL, you first need to establish a connection with the database. PHP provides some built-in function libraries to achieve this purpose. One of the common methods is to use the mysqli_connect() function.

For example, the following code will establish a connection with the local MySQL server:

$servername = "localhost"; 
$username = "root"; 
$password = ""; 
$database = "mydatabase"; 

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

if (!$conn) { 
    die("Connection failed: " . mysqli_connect_error()); 
}

2. Query the database

After the connection is successful, we can execute SQL queries. In PHP, use the mysqli_query() function to execute SQL queries.

For example, the following code will query all the information in the students table:

$sql = "SELECT * FROM students"; 
$result = mysqli_query($conn, $sql);

It should be noted that after executing the SQL query, $result returns an object (mysqli_result), not an array .

3. Convert the query results into an array

Next, we need to convert the returned object into a standard array in PHP. This can be achieved through the mysqli_fetch_assoc() function, which returns a row of records in the query results in the form of an associative array.

The following is a sample code to convert the query results into an array:

$rows = array(); 
while($row = mysqli_fetch_assoc($result)) { 
    $rows[] = $row; 
}

The above code creates an empty array $rows and stores each row of query results into the array in a while loop . The mysqli_fetch_assoc() function is used in the loop to convert each row of query results into an associative array, and the [] operator is used at the end of the array to add it to the $rows array.

4. Complete code

To sum up, the following is a complete sample code that shows how to connect to the database through PHP, query the database and convert the results into an array.

$servername = "localhost"; 
$username = "root"; 
$password = ""; 
$database = "mydatabase"; 

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

if (!$conn) { 
    die("Connection failed: " . mysqli_connect_error()); 
}

$sql = "SELECT * FROM students"; 
$result = mysqli_query($conn, $sql);

$rows = array(); 
while($row = mysqli_fetch_assoc($result)) { 
    $rows[] = $row; 
}

mysqli_close($conn);

5. Summary

In Web development, converting query results into PHP array format is a very common operation. Execute the SQL query through the mysqli_query() function and convert the results into a PHP array through the mysqli_fetch_assoc() function. The above sample code shows how to implement this function, and you can also modify and change it according to your needs.

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