Question

我需要根据inner join字段值，根据不同条件设置doc_type。

这是架构

Person (
  ...
  doc_type VARCHAR2(40),
  doc_series VARCHAR2(4),
  doc_number VARCHAR2(6),
  doc_date DATE
)

Document (
  id INTEGER,
  type VARCHAR2(40),
  series VARCHAR2(4),
  number VARCHAR2(6),
  date DATE
)

例如，如果doc_type值为01，我需要按doc_type和doc_series列进行加入，如果doc_type值为02然后加入应该由doc_type，doc_series，doc_number和doc_date完成。

像这样的东西

SELECT d.* FROM document d
INNER JOIN person p ON
(CASE when d.doc_type = '01' then
  p.doc_type = d.type AND
  p.doc_series = d.series
      when d.doc_type = '02' then
  p.doc_type = d.type AND
  p.doc_series = d.series AND 
  p.doc_number = d.doc_number AND
  p.doc_date = d.doc_date
);

如何在Oracle DB中执行此操作？

Answer 1

我认为你需要这个

SELECT d.* 
FROM document d
INNER JOIN person p ON p.doc_series = d.series AND
( d.doc_type = '01' AND p.doc_type = d.type) OR
( d.doc_type = '02' AND p.doc_type = d.type AND p.doc_number = d.doc_number AND
  p.doc_date = d.doc_date)

Answer 2

SELECT d.* FROM document d
INNER JOIN person p ON (
(d.doc_type = '01' AND p.doc_type = d.type AND p.doc_series = d.series)
OR
( d.doc_type = '02' AND p.doc_type = d.type AND p.doc_series = d.series AND 
  p.doc_number = d.doc_number AND
  p.doc_date = d.doc_date)
);

Answer 3

我宁愿使用union来连接符合条件的表：

   SELECT d.* FROM document d
INNER JOIN person p ON
  p.doc_type = d.type AND
  p.doc_series = d.series
where d.doc_typ = '01'
UNION ALL
SELECT d.* 
FROM document d
INNER JOIN person p ON
  p.doc_type = d.type AND
  p.doc_series = d.series AND 
  p.doc_number = d.doc_number AND
  p.doc_date = d.doc_date
where d.doc_typ = '02'

Answer 4

如果你真的在寻找CASE，试试这个：

SELECT d.* 
FROM document d
INNER JOIN person p ON 
  (CASE when (p.doc_type = d.type AND
            p.doc_series = d.series) then
            '01'
      when ( p.doc_type = d.type AND
             p.doc_series = d.series AND 
             p.doc_number = d.doc_number AND
             p.doc_date = d.doc_date) then
             '02'
    end ) = p.doc_type;

由于您没有正确提及表中的列名，我使用了您提供的查询。请检查列并运行它。希望它有所帮助。

如何按条件使INNER JOIN在不同的字段上

4 个答案: