从一个表中选择所有记录，并在第二个表中没有另一个记录的情况下返回空值

Question

对于此特定查询，我看起来很高，也没有看到它。

我们有两张表;帐户表，然后访问表。我想要返回完整的帐户名称列表，并填写相应的字段为null或正确的年份等。此数据用于SSRS中的矩阵报告。

样本：

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 

，我需要选择每周访问和显示那些有过一个完整的访问，然后将账户不具有访问。

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

请纠正我，如果我拨错

选择TO_CHAR（v.visitdate， 'YYYY'）年，

TO_CHAR（v.visitdate， 'WW'）较弱，a.accountname，v.visitaction

从一个帐户，访问v

其中a.accountname = v.ACCCOUNTNAME

和TO_CHAR（v.visitdate， 'WW'）= TO_CHAR（SYSDATE， 'WW'）

UNION ALL

选择TO_CHAR（SYSDATE， 'YYYY'）年，

TO_CHAR（SYSDATE， 'WW'）弱，a.accountname， '完全'

从占一个

其中a.accountname不是（从访问v选择v.ACCCOUNTNAME

其中TO_CHAR（v.visitdate， 'WW'）= TO_CHAR（SYSDATE， 'WW'））;

Answer 2

以下的答案必须假定

A）你想每星期看到一个给定的范围内，是否有账户是在那一周或不访问。
B）您想查看每周的所有账户
C）对于在给定周内访问的账户，请显示其实际的VisitAction。 D）对于在给定周内未被访问的账户，显示“未完成”作为VisitAction。

如果所有这些都是这种情况，那么以下查询可能会做你所需要的。有一个正常运作的sqlfiddle例如，你可以在这里玩：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); 

我希望帮助。