存在SQL Server的位置

Question

I have the following statement which gets clients over the age of 80

SELECT
    C.ClientID, 
    C.surname  + C.forename As Name,
    CONVERT(VARCHAR(10),  C.DateOfBirth, 103) AS DOB,
    S.SchemeID,
    [Status]
FROM 
    vClients C
INNER JOIN
    vClientSchemes S ON C.ClientID = S.ClientID
INNER JOIN
    vEvents E ON C.ClientId = E.ClientID
WHERE
    (DATEDIFF(yy, C.DateOfBirth, GetDate()) - 
       CASE WHEN((MONTH(DateOfBirth) * 100 + DAY(C.DateOfBirth)) >   (MONTH(GetDate()) * 100 + DAY(GetDate()))) 
              THEN 1 ELSE 0 END) > 80
    AND (DATEDIFF(yy, DateOfBirth, GetDate()) - 
        CASE WHEN((MONTH(DateOfBirth) * 100 + DAY(C.DateOfBirth)) >      
                   (MONTH(GetDate()) * 100 + DAY(GetDate()))) 
             THEN 1 ELSE 0 END) < 100
    AND C.[Status] = 0 
    AND S.SchemeID = 3

However from the result I also need to get the date of when they were last used by the service. This is achieved by querying the table with the following columns

EventId, EventDate, ClientID

So from the events date using the following query. So far I have

SELECT ClientID 
FROM vEvents 
WHERE EventDate > DATEADD(year,-1,GETDATE()) 

But I cant seem to link the two queries

Answer 1

Your where predicates are nonSARGable because you have wrapped your columns in functions. You could make this SARGable AND a lot simpler like this.

WHERE DateOfBirth < DATEADD(Year, -80, cast(getdate() as date)
AND DateOfBirth > DATEADD(Year, -100, cast(getdate() as date)
AND C.[Status] = 0 
AND S.SchemeID = 3

For your actual question you could use MAX(EventDate) and group by the rest of the columns, or you could use ROW_NUMBER.

Answer 2

It looks like you already have access to the vEvents table in your query through alias E . You should be able to add the filter you indicated by adding:

AND E.EventDate > DATEADD(year, -1, GETDATE())

The ClientID should be the same from the vEvents table as it is from your vClients table, due to the inner join, and you're already selecting it.

Answer 3

Yep marc_2 you were right just needed to add the condition and a distinct as well, but remove the select on the EventDate

SELECT
distinct C.ClientID, 
C.surname  + C.forename As Name,
CONVERT(VARCHAR(10),  C.DateOfBirth, 103) AS DOB
FROM vClients C
inner join vClientSchemes S on C.ClientID = S.ClientID
inner join vEvents E ON C.ClientId = E.ClientID
WHERE
(DATEDIFF(yy,C.DateOfBirth,GetDate()) - 
CASE WHEN((MONTH(DateOfBirth)*100 + DAY(C.DateOfBirth)) > (MONTH(GetDate())*100 + DAY(GetDate()))) THEN 1 ELSE 0 END)> 80
 AND (DATEDIFF(yy,DateOfBirth,GetDate()) - CASE WHEN((MONTH(DateOfBirth)*100 + DAY(C.DateOfBirth)) > (MONTH(GetDate())*100 + DAY(GetDate()))) THEN 1 ELSE 0 END) <100
AND C.[Status] = 0 AND  S.SchemeID = 3 AND EventDate > DATEADD(year,-1,GETDATE()) order by C.clientid