I'm not 100% sure what you are looking for but It would seem that DATEPART would be your friend as it appears you are trying to grab the year and month from a datetime field.

Here are some examples...

DECLARE @somedate DATETIME = GETDATE()

SELECT

@somedate AS myDate,

DATEPART(year, @somedate) AS justYear,

DATEPART(month, @somedate) AS justMonth,

'5' + CAST(DATEPART(year, @somedate) AS VARCHAR(4)) + CAST(DATEPART(month, @somedate) AS VARCHAR(2)) AS endResult