SQL Server 2017

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CREATE TABLE t(i INT, c VARCHAR(10));
INSERT INTO t(i,c) VALUES (1, 'a'), (2, 'b'), (3, 'c'), (4, 'd'), (5, 'e')
5 rows affected

SELECT * FROM t;


i
c


1
a

2
b

3
c

4
d

5
e


    WITH CTE AS
    (
    SELECT MIN(i) As firstI,
           STRING_AGG(
                   (IIF(i % 2 = 0, ' OR ', ' AND '))+c
               , '') WITHIN GROUP (ORDER BY i)
           AS r
    FROM t
    )
    
    SELECT STUFF(r, 1, IIF(firstI % 2 = 0, 4, 5), '')
    FROM CTE;


(No column name)


a OR b AND c OR d AND e