SO-37925176

DECLARE @table TABLE (
     ID INT IDENTITY(1, 1)
            PRIMARY KEY,
     A1 CHAR(2),
     A2 CHAR(2),
     A3 CHAR(2),
     A4 CHAR(2)
    );

INSERT  INTO @table
        (A1, A2, A3, A4)
VALUES  ('P1', 'P4', 'P2', 'P3'),
        ('P2', 'P3', 'P1', 'P3');

SELECT  t.ID,
        t.A1,
        t.A2,
        t.A3,
        t.A4,
        STUFF((
               SELECT   ' | ' + unpvt.Val
               FROM     @table UNPIVOT ( Val FOR Col IN (A1, A2, A3, A4) ) unpvt
               WHERE    unpvt.ID = t.ID
               ORDER BY unpvt.Val
              FOR
               XML PATH('')
              ), 1, 3, '') AS ORDERED_DATA
FROM    @table AS t;

/*
ID	A1	A2	A3	A4	ORDERED_DATA
1	P1	P4	P2	P3	P1 | P2 | P3 | P4
2	P2	P3	P1	P3	P1 | P2 | P3 | P3
*/