从一个表中选择所有记录，并在第二个表中没有其他记录的情况下返回空值

Question

I have looked high and low for this particular query and have not seen it.

We have two tables; Accounts table and then Visit table. I want to return the complete list of account names and fill in the corresponding fields with either null or the correct year etc. this data is used in a matrix report in SSRS.

sample:

Acounts:
AccountName  AccountGroup  Location
Brown Jug    Brown Group   Auckland
Top Shop     Top Group     Wellington
Super Shop   Super Group   Christchurch

Visit:
AcccountName  VisitDate   VisitAction
Brown Jug     12/12/2012  complete
Super Shop    1/10/2012   complete

I need to select weekly visits and show those that have had a complete visit and then the accounts that did not have a visit.

e.g.
Year  Week  AccountName  VisitStatus       for week 10/12/2012 should show
2012    50  Brown Jug    complete
2012    50  Top Group    not complete
2012    50  Super Shop   not complete

e.g.
Year  Week  AccountName  VisitStatus      for week 1/10/2012 should show
2012     2  Brown Jug    not complete
2012     2  Top Group    not complete
2012     2  Super Shop   complete

Answer 1

The following answer assumes that

A) You want to see every week within a given range, whether any accounts were visited in that week or not.
B) You want to see all accounts for each week
C) For accounts that were visited in a given week, show their actual VisitAction.
D) For accounts that were NOT visited in a given week, show "not completed" as the VisitAction.

If all those are the case then the following query may do what you need. There is a functioning sqlfiddle example that you can play with here: http://sqlfiddle.com/#!3/4aac0/7

--First, get all the dates in the current year.
--This uses a Recursive CTE to generate a date 
--for each week between a start date and an end date
--In SSRS you could create report parameters to replace
--these values.
WITH WeekDates AS
(
  SELECT CAST('1/1/2012' AS DateTime) AS WeekDate
  UNION ALL
  SELECT DATEADD(WEEK,1,WeekDate) AS WeekDate
  FROM WeekDates
  WHERE DATEADD(WEEK,1,WeekDate) <= CAST('12/31/2012' AS DateTime)
),
--Next, add meta data to the weeks from above. 
--Get the WeekYear and WeekNumber for each week.
--Note, you could skip this as a separate query 
--and just included these in the next query, 
--I've included it this way for clarity
Weeks AS
(
  SELECT
    WeekDate,
    DATEPART(Year,WeekDate) AS WeekYear,
    DATEPART(WEEK,WeekDate) AS WeekNumber
  FROM WeekDates
), 
--Cross join the weeks data from above with the
--Accounts table.  This will make sure that we 
--get a row for each account for each week.  
--Be aware, this will be a large result set 
--if there are a lot of weeks & accounts (weeks * account)
AccountWeeks AS 
(
  SELECT 
    * 
  FROM Weeks AS W
  CROSS JOIN Accounts AS A
)
--Finally LEFT JOIN the AccountWeek data from above
--to the Visits table.  This will ensure that we 
--see each account/week, and we'll get nulls for 
--the visit data for any accounts that were not visited
--in a given week.
SELECT 
  A.WeekYear,
  A.WeekNumber,
  A.AccountName,
  A.AccountGroup,
  IsNull(V.VisitAction,'not complete') AS VisitAction
FROM AccountWeeks AS A
LEFT JOIN Visits AS V
ON A.AccountName = V.AccountName
AND A.WeekNumber = DATEPART(WEEK,V.VisitDate)
--Set the maxrecursion number to a number 
--larger than the number of weeks you will return
OPTION (MAXRECURSION 200);

I hope that helps.

Answer 2

please correct me if am worng

select to_char(v.visitdate,'YYYY') year,

to_char(v.visitdate,'WW') WEAK,a.accountname,v.visitaction

from accounts a,visit v

where a.accountname=v.ACCCOUNTNAME

and to_char(v.visitdate,'WW')=to_char(sysdate,'WW')

union all

select to_char(sysdate,'YYYY') year,

to_char(sysdate,'WW') WEAK,a.accountname,'In Complete'

from accounts a

where a.accountname not in ( select v.ACCCOUNTNAME

from visit v where to_char(v.visitdate,'WW')=to_char(sysdate,'WW'));