如何選擇某些列中具有相同值的所有行

Question

我是sql的新手，所以請善待。

假設我必須顯示所有具有相同電話號碼的employee_ids（兩列都在同一個表中）

我如何繼續這個問題內部聯接或什么。

Answer 1

怎么樣

SELECT *
FROM Employees
WHERE PhoneNumber IN (
    SELECT PhoneNumber
    FROM Employees
    GROUP BY PhoneNumber
    HAVING COUNT(Employee_ID) > 1
    )

SQL Fiddle DEMO

Answer 2

SELECT * FROM employees e1, employees e2 
WHERE e1.phoneNumber = e2.phoneNumber 
AND e1.id != e2.id;

更新 ：為了更好的性能和更快的查詢，在*之前添加e1好的

SELECT e1.* FROM employees e1, employees e2 
WHERE e1.phoneNumber = e2.phoneNumber 
AND e1.id != e2.id;

Answer 3

你可以在沒有JOIN情況下做到這一點：

SELECT *
FROM (SELECT *,COUNT(*) OVER(PARTITION BY phone_number) as Phone_CT
      FROM YourTable
      )sub
WHERE Phone_CT > 1
ORDER BY phone_number, employee_ids

演示： SQL小提琴

Answer 4

select *
from Table1 as t1
where
    exists (
        select *
        from Table1 as t2 
        where t2.Phone = t1.Phone and t2.id <> t1.id
    )

sql小提琴演示