Pivot a table to repeat the first column for each following column
This will work wit Access and SQL-Server

SELECT ID, A AS Fieldx
FROM tbl 
UNION ALL
SELECT ID, B
FROM tbl 
UNION ALL
SELECT ID, C
FROM tbl
UNION ALL
SELECT ID, D
FROM tbl;


specific for SQL-Server:

SELECT ID, FieldX FROM 
   (SELECT ID,A,B,C,D   FROM tbl) p
UNPIVOT
   (FieldX for dummyID in (A,B,C,D)) as dummyField 


Additional information can be found here