SQLite 3.39

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CREATE TABLE test (col1 INT, col2 INT, col3 INT);
✓
INSERT INTO test VALUES 
(1,2,3), (1,4,5), (3,2,1);
✓
SELECT * FROM test;


col1
col2
col3


1
2
3

1
4
5

3
2
1


SELECT CASE WHEN SUM(CASE WHEN col1 = 1 THEN 1 END) = 1 THEN 'col1'
            WHEN SUM(CASE WHEN col2 = 1 THEN 1 END) = 1 THEN 'col2'
            WHEN SUM(CASE WHEN col3 = 1 THEN 1 END) = 1 THEN 'col3'
            ELSE 'none'
            END where_only_one_1
FROM test;


where_only_one_1


col3