选择声明 - 仅在条件时

Question

Take a look in the table below:

Status ----------------- Email
Approved ----------------john@john.com 
Canceled --------------- john@john.com 
Canceled --------------- charles@charles.com 
Canceled --------------- charles@charles.com 
Canceled --------------- charles@charles.com 

I execute the query

"SELECT DISTINCT Status, Email FROM dbo.sales":

Status ----------------- Email
Approved --------------- john@john.com 
Canceled ----------------john@john.com 
Canceled --------------- charles@charles.com 

I'd like to set up a query to select the rows that have the status "Canceled" ONLY WHEN there is not a row with the same email with the status "Approved".

In other words, I'd to select only the last entry (Canceled - charles@charles.com) in this example.

Is it possible? Thanks in advance.

Answer 1

Select distinct status,email
From dbo.sales
Where email Not In ( select email from dbo.sales
                      Where status='Approved' )

Answer 2

Try this

Select  Status, Email
FROM dbo.sales
WHERE Status = 'Canceled' AND 
NOT EXIST(Select  Status, Email FROM dbo.sales Where Status='Approved')
GROUP BY Status, Email

Answer 3

Assuming you have only 'Approved' and 'Cancelled' as values for Status column:

select status, email from dbo.sales
where email not in (select email from dbo.sales where status = 'Approved')
group by email

Answer 4

You can use following queries:

Method 1 :

SELECT DISTINCT t.status, t.email
FROM dbo.test t
LEFT JOIN (SELECT * FROM test WHERE STATUS = 'Approved')z ON z.email = t.email
WHERE t.STATUS = 'Canceled'
    AND z.STATUS IS NULL

Method 2:

SELECT DISTINCT status, email
FROM dbo.sales t
WHERE t.STATUS = 'Canceled'
  and t.email Not In (  SELECT email 
                        FROM dbo.sales
                        WHERE status='Approved' )

Answer 5

If this is about cancelled emails only, you could try EXCEPT:

SELECT Email FROM dbo.sales WHERE Status = 'Canceled'
EXCEPT
SELECT Email FROM dbo.sales WHERE Status = 'Approved'
;

or, if Status must be included in the output:

SELECT Status,     Email FROM dbo.sales WHERE Status = 'Canceled'
EXCEPT
SELECT 'Canceled', Email FROM dbo.sales WHERE Status = 'Approved'
;

If you actually meant to display emails that are either always approved or always cancelled, one way would be to repeat the above logic for each subset:

(
SELECT Status,     Email FROM dbo.sales WHERE Status = 'Canceled'
EXCEPT
SELECT 'Canceled', Email FROM dbo.sales WHERE Status = 'Approved'
)
UNION ALL
(
SELECT Status,     Email FROM dbo.sales WHERE Status = 'Approved'
EXCEPT
SELECT 'Approved', Email FROM dbo.sales WHERE Status = 'Canceled'
)
;

Alternatively, however, you could try grouping and counting distinct Status values in the groups:

SELECT
  MIN(Status) AS Status,
  Email
FROM
  dbo.sales
GROUP BY
  Email
HAVING
  COUNT(DISTINCT Status) = 1
;

This other method would work for any number of possible Status es.