The following code example demonstrates how to use the OPENJSON rowset function to return the details of orders for IDs provided in a comma-separated list:

USE WideWorldImporters; 
DECLARE @orderIds AS VARCHAR(100) = '1,3,7,8,9,11'; 
SELECT o.OrderID, o.CustomerID, o.OrderDate  
FROM Sales.Orders o 
INNER JOIN (SELECT value FROM OPENJSON('[' + @orderIds + ']' )) x ON x.value= o.OrderID; 

Here is the list of orders produced by the preceding query:

OrderID     CustomerID  OrderDate
----------- ----------- ----------
1           832         2013-01-01
3           105         2013-01-01
7           575         2013-01-01
8           964         2013-01-01
9           77          2013-01-01
11          586         2013-01-01

In this example, the input argument is wrapped with square brackets to create a proper JSON text and the OPENJSON function is invoked without the path argument. OPENJSON created one row for each element from the JSON array and that is exactly what you needed.