Group by Customer ID where Another Column is only Contains a specific set of Values
<p>Wasn't sure how to ask this one.</p>

<p>I have table with 4 columns in it.  They are PK, CustomerID, Language, and Date.  The Customer ID can be the same for multiple rows in the file. The Language is a numerical value from 1-8 representing different languages. The Date is the first of any given month.  So, for 10 rows in the table, it is legitimate for the CustomerID to be 123 for all 10 rows, the language '1' for all ten rows, and the date '1/1/2015' for all 10 rows.  Essentially, I have a lot of subsets in this table where the PK would create a row level distinction.</p>

<p>On to what I am trying to do.  I need to group by the customer ID, for 3 specific dates ('10/01/2015', '11/01/2015', '12/01/2015'), where the only value found for language is 1.  Meaning, if on 10/01/05, customerID 123 has 10 rows and 9 are language '1', and the 10th row is language '2', I wouldn't want that to return in my results.</p>

<p>At the end, I need a list of the customer ID's that from those 3 dates that only have '1' as there language and do not have any other languages in their rows. </p>

<p>This has gotten beyond my skill.  I appreciate any help as I feel like it is simpler than I am making it out to be. </p>