MSSQL (Microsoft SQL Server) is a popular database management system used by many businesses and organizations. If you are a PHP developer looking to connect your PHP application to an MSSQL database, this tutorial is for you.

First, you will need to ensure that you have the necessary components installed on your system. You will need the MSSQL drivers for PHP, as well as the MSSQL extension for PHP. You can check if these components are installed by creating a PHP file with the following code:

<?php
phpinfo();
?>

Run this PHP file in your web browser and look for the "mssql" and "sqlsrv" sections. If these sections are present, you have the necessary components installed. If not, you will need to install them before proceeding.

Next, you will need to create a connection to the MSSQL database. You can do this using the sqlsrv_connect() function, which takes three parameters: the server name, the username, and the password.

<?php
$serverName = "serverName\sqlexpress";
$connectionInfo = array( "Database"=>"dbName", "UID"=>"username", "PWD"=>"password");
$conn = sqlsrv_connect( $serverName, $connectionInfo);

if( $conn ) {
     echo "Connection established.<br />";
}else{
     echo "Connection could not be established.<br />";
     die( print_r( sqlsrv_errors(), true));
}
?>

If the connection is successful, the "Connection established" message will be displayed. If the connection fails, an error message will be displayed.

Once you have established a connection to the MSSQL database, you can execute SQL queries using the sqlsrv_query() function. This function takes two parameters: the connection resource and the SQL query.

<?php
$sql = "SELECT * FROM table_name";
$stmt = sqlsrv_query( $conn, $sql);

if( $stmt === false) {
     die( print_r( sqlsrv_errors(), true));
}
?>

If the query is successful, the sqlsrv_query() function will return a statement resource. You can then use the sqlsrv_fetch_array() function to retrieve the results of the query and process them as needed.

<?php
while( $row = sqlsrv_fetch_array( $stmt, SQLSRV_FETCH_ASSOC)) {
     echo $row['column_name'] . "<br />";
}
?>

That's it! With these basic steps, you should be able to connect your PHP application to an MSSQL database and execute SQL queries. Happy coding!