In Access query how to check if a group of records has the same value

Question

In the following query for each group of "first", I want to check if the Values on field "Second" are true.
For example, in the "first" field for "A" Group if the related values on the "second" field are true, the "Third" field must display "True" for both records, and if the values are false or are different the "third field value must display "False"
I reached this approach by creating new query grouping the "First" values of the main query then I Called the related values on the main query by Dlookup where its group values are equal, but it is very slow.

First	Second	Third
A	True	True
A	True	True
B	False	False
B	Fasle	False
C	True	False
C	Fasle	False

Answer 1

Use Exists in a simple query:

SELECT 
    Check.[First], 
    Check.Second, 
    Not Exists 
        (Select T.[First] From Check As T 
        Where T.[First] = Check.[First] And T.Second=False) AS Third
FROM 
    [Check];

Output (in Danish: Ja = True, Nej = False):