的Oracle SQL：查找并删除重复（在不同的列值相同）

Question

的Oracle SQL：如何找到并删除重复

我只有只读访问Oracle（仅可以使用SELECT命令）。

逻辑：两个用户 'A' & 'B' 由具有相同公司名称&名字

列提取：

ID of A 
ID of B 
Company Name of A 
Company Name of B 
First Name of A 
First Name of B 

我使用以下查询：

select a.id, b.id, a.name, b.name, a.company, b.company from 
(select id, company, name where country = 'USA') a, 
(select id, company, name where country = 'UK') b 
where a.id <> b.id 
and lower(a.company) = lower(b.company) 
and a.username = b.username 

---

在这里我得到的每一行两次（请参见下表）：

A_ID .......... B_ID .......... A_NAME .... ...... B_NAME .......... A_COMPANY .......... B_COMPANY

3592382 .... 1977967 .... Peter ...... ..........彼得................. ABC ..................... A.B.C.

1977967 .... 3592382 .... Peter ................ Peter ................. A.B.C. ..................... A.B.C.

5949363 .... 5941818 .... Joseph ............ Joseph .............. X.Y.Z. ........................ X.Y.Z.

5941818 .... 5949363 .... Joseph ............ Joseph .............. X.Y.Z. ........................ X.Y.Z.

Answer 1

你有几个问题与查询。

1）如果你做select val1,val2 from a, b，你会得到一个cross-join结果。

2）别名表没有from子句。

你说你只有select访问权限。因此你只能得到select的非重复值。

select distinct a.id, b.id, a.name, b.name, a.company, b.company 
from 
(select id, company, name from tablename where country = 'USA') a 
join 
(select id, company, name from tablename where country = 'UK') b 
on a.id = b.id and lower(a.company) = lower(b.company) and a.username = b.username 

Answer 2

您忘记了子查询中的表名。此外，我建议不要让a.col和b.col在双方的值将是相同的（这是）的条件，因为它降低性能并没有增加

SELECT a.id, b.id, a.name, a.company 
FROM tablename a 
JOIN tablename b 
    ON (a.name == b.name AND a.company == b.company AND a.username == b.username) 
WHERE a.country = 'USA' 
    AND b.country = 'UK'