Call to undefined function odbc_connect() message while connecting SAP HANA database

I just go through in google get this instruction this is really helpful for you.

1. Download the SQL Server ODBC driver for your PHP client
   platform. (Registration required.) If the SQL Server ODBC driver
   is not currently available for your platform, check the list of
   ODBC-ODBC Bridge Client platforms. The ODBC-ODBC Bridge is an
   alternative SQL Server solution from Easysoft, which you can
   download from this site.
2. Install and license the SQL Server ODBC driver on the machine where
   PHP is installed. For installation instructions, see the ODBC driver
   documentation. Refer to the documentation to see which environment
   variables you need to set (LD_LIBRARY_PATH, LIBPATH, LD_RUN_PATH,
SHLIB_PATH depending on the driver, platform and linker).

3. Create an ODBC data source in /etc/odbc.ini that connects to the
   SQL Server database you want to access from PHP. For example, this
   SQL Server ODBC data source connects to a SQL Server Express instance
   that serves the Northwind database:

   • Use isql to test the new data source. For example:
     cd /usr/local/easysoft/unixODBC/bin

   ./isql -v MSSQL-PHP

[MSSQL-PHP]
Driver                  = Easysoft ODBC-SQL Server
Server                  = my_machine\SQLEXPRESS
User                    = my_domain\my_user
Password                = my_password

Please copy and paste this script and execute this

<?
/*
PHP MSSQL Example

Replace data_source_name with the name of your data source.
Replace database_username and database_password
with the SQL Server database username and password.
*/
$data_source="data_source_name";
$user="database_username";
$password='database_password';

// Connect to the data source and get a handle for that connection.
$conn=odbc_connect($data_source,$user,$password);
if (!$conn){
    if (phpversion() < '4.0'){
      exit("Connection Failed: . $php_errormsg" );
    }
    else{
      exit("Connection Failed:" . odbc_errormsg() );
    }
}

// This query generates a result set with one record in it.
$sql="SELECT 1 AS test_col";

# Execute the statement.
$rs=odbc_exec($conn,$sql);

// Fetch and display the result set value.
if (!$rs){
    exit("Error in SQL");
}
while (odbc_fetch_row($rs)){
    $col1=odbc_result($rs, "test_col");
    echo "$col1\n";
}

// Disconnect the database from the database handle.
odbc_close($conn);
?>

1. Replace data_source_name, database_username and database_password
   with your SQL Server ODBC data source, login name and password.

2. To run the script under Apache, save the file below your Apache web
   server’s document root directory. For example,
/var/www/apache2-default/php-mssql-connection.phtml. Then view the
file in a web browser:

   http://localhost/php-mssql-connection.phtml
   

3. If your web browser is not running on the same machine as the web
   server, replace localhost with the web server’s host name or IP
   address.

4. To run the script from the command line, save the file.

   For example,
   /tmp/php-mssql-connection.php. Then run $ php
   /tmp/php-mssql-connection.php.

further more Details Refer this LINK