SQL计数和组重复

Question

请告知解决问题的最佳方法.

我有一个问题,弄清楚如何计算表中的重复项,如下所示

Street       | City

avenue 123   | New York
avenue 123   | New York
avenue 20    | New York
avenue 35    | Chicago
avenue 12    | Chicago
avenue 123   | Chicago
avenue 12    | Chicago
avenue 12    | Chicago

我想在同一个城市有多个重复的街道,结果如下？

结果:

Street     | City | Duplicates

avenue 123 | New York | 2
avenue 12  | Chicago | 3

Answer 1

使用GROUP BY,COUNT和HAVING:

 SELECT Street, City, COUNT(*)
 FROM yourtable
 GROUP BY Street, City
 HAVING COUNT(*) > 1

看到它在线工作:sqlfiddle

Answer 2

尝试 ：

SELECT street, city, COUNT(*) AS duplicates
FROM yourtable
GROUP BY street, city
HAVING COUNT(*) >1

HAVING COUNT(*) > 1如果您还想显示没有重复的行，请将其删除。