Question

如何因数据输入错误而找到重复数据？我想找到拥有相同PhoneNumber的客户。我需要列出客户FirstName和LastName

有什么想法？感谢

修改

当我运行此查询时：

Select FirstName, LastName, PhoneNumber
From Customer

我得到了这个结果：

Person  One 12345
Person  Two 23456
Third   Person  34567
First   Person  12345
Person  Three   34567

解决方案

这是Bulat答案的一个版本，到目前为止是最好的。其他答案没有给出我需要的结果。

SELECT
  c1.FirstName as FirstName1,
  c1.LastName as LastName1,
  c2.FirstName as FirstName2, 
  c2.LastName as LastName2,
  c1.PhoneNumber
FROM 
  Customer c1 INNER JOIN 
  Customer c2 ON c1.Phone = c2.Phone AND c1.CustomerID < c2.CustomerID

Answer 1

此查询会为您提供duplicata

select firstname, lastname 
from customers
group by phonenumber, firstname, lastname
having count(phonenumber) > 1

按照phonenumber分组所有结果。
仅显示多次出现（重复）的人。

Answer 2

您需要通过电话号码字段将CUstomers表连接到自己：

SELECT
  c1.Name as Name1,
  c1.Surname as Surname1,
  c2.Name as Name2, 
  c2.Surname as Surname2,
  c.Phone
FROM 
  Customers c1 INNER JOIN 
  Customers c2 ON c1.Phone = c2.Phone AND c1.id < c2.id

注意：与其他答案不同，即使姓名和姓氏不匹配，也会返回具有相同电话号码的客户。

Answer 3

电话号码重复：

SELECT phone_number
FROM   customers
GROUP
    BY phone_number
HAVING Count(*) > 1

电话号码重复的客户

SELECT *
FROM   customers
 INNER
  JOIN (
        SELECT phone_number
        FROM   customers
        GROUP
            BY phone_number
        HAVING Count(*) > 1
       ) As duplicate_phone_numbers
    ON duplicate_phone_numbers.phone_number = customers.phone_number

在同一个表中查找错误/重复数据

3 个答案:

电话号码重复：

电话号码重复的客户