sql : select 查询无重复数据

Question

select ft.id, ft.qty, st.data from first_table ft
left outer join second_table st on ft.id = st.id
where ft.id = '1abc'

我有两个 table。这些 table 的架构如下

无 1 table 架构

Id	Desc	Qty
1abc	One	3
1abc	two	6

无 2 table 架构

Id	Data
1abc	12ab
1abc	23ab
1abc	z99c

加入查询后数据显示错误

Id	Desc	Qty	Data
1abc	One	3	12ab
1abc	two	6	12ab
1abc	One	3	23ab
1abc	two	6	23ab
1abc	One	3	z99c
1abc	two	6	z99c

以下是它应该在 crystal 报告中显示的正确方式。请建议我该怎么做。

Id	Qty	Data
1abc	3	12ab
	6	23ab
		z99c

Answer 1

您似乎想在单独的列中列出值。这通常最好在应用层完成，但您也可以使用 SQL:

select min(id), min(qty), min(data)
from ((select id, null as qty, null as data,
              row_number() over (order by id) as seqnum
       from table1
       group by id
      ) union all
      (select null as id, qty, null as data,
              row_number() over (order by qty) as seqnum
       from table1
       group by qty
      ) union all
      (select null as id, null as qty, data,
              row_number() over (order by data) as seqnum
       from table2
       group by data
      )
     ) x
group by seqnum;

sql : select 查询无重复数据

sql : select query without duplicate data

sql

select

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