使用具有重複值的列聯接2個表;考慮到第一排

Question

我想用ID柱加入EMP和SAL表。如果Sal表中的ID s表中的第表的第一行爲sal。結果應該是：

Answer 1

這裏是你如何與row_number窗函數管理此：

select * from emp e 
join (select *, row_number() over(partition by id order by(select null)) rn from sal) s 
    on e.id = s.id and s.rn = 1 

Answer 2

使用窗函數ROW_NUMBER()

SELECT SAL.ID, SAL.Gross, Sal.Net, Sal.Deductions, Emp.Name FROM EMP JOIN 
(SELECT *, 
ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Net) rown FROM SAL 
) SAL on EMP.ID = SAL.ID 
WHERE SAL.rown = 1