SQL查询具有多于一列重复一个值的行

Question

I have table like:

I wanted to get all DeviceID which have key=1 more then 1 time. Like device ID= 3 have two rows with key=1, same as 4. What is the query to get that result?

I tried a lot but couldn't find any solution. It seems not possible with group by and having clause.

Answer 1

You should be able to use GROUP BY and HAVING to get the DeviceIds with more than one row:

select deviceid
from yourtable
where key = 1
group by deviceid
having count(key) > 1

See SQL Fiddle with Demo

Answer 2

Try something like this:

SELECT DeviceID
FROM YourTable 
WHERE key = 1
GROUP BY DeviceID
HAVING COUNT(*) > 1

Answer 3

Use this:
SQL Fiddle

SELECT DevID
FROM Devices
WHERE KeyID = 1
GROUP BY DevID
HAVING COUNT(*) > 1;