SELECT *
FROM (
SELECT 序號, 題幹, A選項 AS 選項, 'A' AS 答案
FROM tiku
UNION ALL
SELECT 序號, 題幹, B選項 AS 選項, 'B' AS 答案
FROM tiku
UNION ALL
SELECT 序號, 題幹, C選項 AS 選項, 'C' AS 答案
FROM tiku
UNION ALL
SELECT 序號, 題幹, D選項 AS 選項, 'D' AS 答案
FROM tiku
) AS t
WHERE 選項 NOT IN (
SELECT A選項
FROM tiku
UNION
SELECT B選項
FROM tiku
UNION
SELECT C選項
FROM tiku
UNION
SELECT D選項
FROM tiku
GROUP BY A選項, B選項, C選項, D選項
HAVING COUNT(*) > 1
)
上述SQL查詢語句將題庫表中的所有選項轉化為壹列數據，並將其按照序號、題幹、選項和答案的順序輸出。同時，使用子查詢的方式統計出所有4個選項中重復出現的選項值，並將這些選項從輸出結果中剔除。