[英]Cross join on a group based on the condition in SQL Server
我没有看到生成丢失数据的方法。 日历表方法是将所有代码与所有考试交叉加入。 然后,将此表连接到Item
并按顺序获取所需的结果:
WITH cte AS (
SELECT *
FROM (SELECT DISTINCT Code FROM Item) AS C
CROSS JOIN Exam
)
SELECT
t1.Code,
t2.Item,
t1.Exam
FROM cte t1
LEFT JOIN Item t2
ON t1.Code = t2.Code AND
t1.Exam = t2.Exam
ORDER BY
t1.Code,
CASE WHEN t2.Item IS NOT NULL THEN 0 ELSE 1 END,
t1.Exam
在这里演示:
这应该产生你需要的东西。 我正在使用UNION来组合CROSS JOIN和项表,然后分组以确保删除NULL。
SELECT code, max(item) as item, exam
FROM
(SELECT distinct i.code, null as item, e.exam FROM exam e cross join item i
union all
SELECT code, item, exam
FROM item) u
group by code, exam
order by code, exam
你可以试试这个
SELECT A.Code, i.Item, A.Exam
FROM
(
SELECT Code,e.Exam
FROM Item i
CROSS JOIN Exam e
GROUP BY Code,e.Exam
) A
LEFT JOIN Item i ON i.Code= A.Code AND i.Exam = A.Exam
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