Getting the 1st date of the current and previous month in U-SQL

How to get in U-SQL:

• the 1st date of the current month
• the 1st date of the previous month?

If I was using SQL I would write the following query (any idea how to write it in U-SQL?):

WHERE MyDate BETWEEN DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) AND DATEADD(MONTH, DATEDIFF(MONTH, 0, getdate()), 0)

You can use C# expressions for that:

DECLARE @startDayThisMonth DateTime = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
DECLARE @startDayPreviousMonth DateTime = new DateTime(DateTime.Now.Year, DateTime.Now.Month - 1, 1);

@data = 
    SELECT 
        x
     FROM 
        y
    WHERE
        MyDate BETWEEN @startDate AND @endDate;

Examples can be found at this site.