This extension requires the Microsoft ODBC Driver for SQL Server

Issue

Some time you may facing the following error when trying to connect to MS SQL Server from PHP using the sqlsrv_connect() function:

Error As follows: Array ( [0] => Array ( [0] => IMSSP [SQLSTATE] => IMSSP [1] => -49 [code] => -49 [2] => 
This extension requires the Microsoft ODBC Driver for SQL Server. 
Access the following URL to download the ODBC Driver for SQL Server for x64: https://go.microsoft.com/fwlink/?LinkId=163712 [message] 
=> This extension requires the Microsoft ODBC Driver for SQL Server. 
Access the following URL to download the ODBC Driver for SQL Server for x64: https://go.microsoft.com/fwlink/?LinkId=163712 ) )

Environment

• CloudLinux 6/7/8

Solution

1. To configure ODBC, please perform the following actions:

1.1 In the /etc/odbcinst.ini, add details about FreeTDS driver:

[FreeTDS]
    Description = MS SQL database access with Free TDS
    Driver      = /opt/alt/freetds/usr/lib64/libtdsodbc.so
    Setup      = /usr/lib64/libtdsS.so
    UsageCount  = 1

    * For i386/i686 lib64 use lib in path

 1.2 Add details about the MSSQL server to /etc/odbc.ini:

[mssql_odbc]
    Description            = MSSQL Server
    Driver                  = FreeTDS  //should have the same name as driver in /etc/odbcinst.ini
    Database                = %DB_NAME% 
    Server                  = %IP%
    Port                    = %PORT%

1.3 Update CageFS:

cagefsctl --update-etc

1.4 Enable PHP extensions:
selectorctl -u %USERNAME% -v %PHP_VERSION% -e pdo_odbc,odbc

1.5 Add the following syntax in the connection script:
$dbh = new PDO("odbc:mssql_odbc", "sa", "%DB_USER%", "%DB_PASS%");

1.6 Also, you need to run the following commands:

/opt/alt/alt-php-config/install_odbc
cagefsctl --force-update
cagefsctl -M

So basically, you need the following PHP extensions:

pdo_odbc,odbc

To enable them, please run the following command:

selectorctl --enable-user-extensions=pdo_dblib,odbc --version=X.X --user=UserName

where x.x depends on PHP version which you use for the website.