ASP +ACCESS 数据库 如何查找某字段值 在当前表4个字段中唯一？
我原来写了一条，发现效率超级低：
sql="select * from tiku where daan='A' and sa not in (select sa from tiku group by sa having count(sa)>1) and sa not in (select sb from tiku group by sb having count(sb)>1) and sa not in (select sc from tiku group by sc having count(sc)>1) and sa not in (select sd from tiku group by sd having count(sd)>1)"
最新回答
客串情人
2024-06-24 01:31:36
SELECT *
FROM (
SELECT 序号, 题干, A选项 AS 选项, 'A' AS 答案
FROM tiku
UNION ALL
SELECT 序号, 题干, B选项 AS 选项, 'B' AS 答案
FROM tiku
UNION ALL
SELECT 序号, 题干, C选项 AS 选项, 'C' AS 答案
FROM tiku
UNION ALL
SELECT 序号, 题干, D选项 AS 选项, 'D' AS 答案
FROM tiku
) AS t
WHERE 选项 NOT IN (
SELECT A选项
FROM tiku
UNION
SELECT B选项
FROM tiku
UNION
SELECT C选项
FROM tiku
UNION
SELECT D选项
FROM tiku
GROUP BY A选项, B选项, C选项, D选项
HAVING COUNT(*) > 1
)
上述SQL查询语句将题库表中的所有选项转化为一列数据，并将其按照序号、题干、选项和答案的顺序输出。同时，使用子查询的方式统计出所有4个选项中重复出现的选项值，并将这些选项从输出结果中剔除。
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