Select multiple columns in a datatable:serverside

ASL

Hi there
I am doing a serverside processing of datatables with coloumn filter and can someone help me to choose multiple columns of 2 different database table to match the datatable column.
this is my part of the Code:

// datatable column index => database column name
0=> 'Issue',
1=> 'Date_raised',
2=> 'lastUpdate',
3=> 'assignedTo',
4=> 'priority',
5=> 'severity',
6=> 'Status',
7=> 'createdBy',
8=> 'Client_ID'

);

$sql = "SELECT Issue, Date_Format(Date_raised,'%m/%e/%Y') as Date,assignedTo,priority,severity,Status,createdBy,Date_Format(lastUpdate,'%m/%e/%Y') as update1,Client_ID,clientdetails.company from issue left join clientdetails on issue.Client_ID = clientdetails.Client_ID";

How can i Show the clientdetails.company in my 8th coloumn of my datatable??
should it be 8 =>'company' ??

Thanks in Advance.