Picking data from database that appeard just once in a month

I have a table and in that bank transactions are recorded. 开发者_StackOverflow社区I want to pull out the users who made transaction just once in a month. That means their transaction count == 1 for that month.

I am recording card_number, timestamp etc..

SELECT * 
FROM transactions
GROUP BY card_number, month
HAVING COUNT(card_number) = 1

Check This

select     Card_Number,
           DATEPART(m, [TimeStamp] )MonthNo,
           COUNT(1) TxnCount
from       Transactions
group by   Card_Number,
           DATEPART(m, [TimeStamp] )
having     COUNT(1)=1

I am assuming that your table structure is somthing like below.

Card_Number int, 
TimeStamp  datetime