SQL 查询在嵌套 select 中使用别名时引发错误

Question

I posted one question today but that was too broad. So, I worked on that and now narrow down to some of parts. However, my query is returning syntax error while just copy paste the same text.

(
SELECT
   TOP (100) PERCENT v_UpdateComplianceStatus.ResourceID, v_UpdateComplianceStatus.Status, CAST(DATEPART(yyyy, v_UpdateInfo.DatePosted) AS varchar(255)) + '-' + RIGHT('0' + CAST(DATEPART(mm, v_UpdateInfo.DatePosted) AS VARCHAR(255)), 2) AS MonthPosted, COUNT(1) AS Count 
FROM
   v_UpdateComplianceStatus 
   INNER JOIN
      v_UpdateInfo 
      ON v_UpdateComplianceStatus.CI_ID = v_UpdateInfo.CI_ID 
   INNER JOIN
      v_R_System 
      ON v_UpdateComplianceStatus.ResourceID = v_R_System.ResourceID 
   inner join
      v_FullCollectionMembership fcm 
      on v_UpdateComplianceStatus.ResourceID = fcm.ResourceID 
WHERE
   (
      v_R_System.Operating_System_Name_and0 like '%Workstation 6.1%' 
      and v_R_System.Obsolete0 = 0
   )
   AND 
   (
      v_UpdateInfo.Severity IN 
      (
         8,
         10
      )
   )
   AND 
   (
      v_UpdateInfo.IsSuperseded = 0
   )
   AND 
   (
      v_UpdateInfo.IsEnabled = 1
   )
   and fcm.CollectionID = 'ABC00328' 
GROUP BY
   v_UpdateComplianceStatus.ResourceID, v_UpdateComplianceStatus.Status, CAST(DATEPART(yyyy, v_UpdateInfo.DatePosted) AS varchar(255)) + '-' + RIGHT('0' + CAST(DATEPART(mm, v_UpdateInfo.DatePosted) AS VARCHAR(255)), 2)) FF
where Status =2
Group By MonthPosted ) E
where E.MonthPosted = E.MonthPosted
order by MonthPosted Desc

If I run the above query it is throwing error at

Group By MonthPosted ) EE 

Not sure why it is giving error.

Msg 102, Level 15, State 1, Line 123
Incorrect syntax near 'EE'.

Some Important things which I discover.

This query works fine if I run some part of it.

(SELECT TOP (100) PERCENT v_UpdateComplianceStatus.ResourceID, v_UpdateComplianceStatus.Status, CAST(DATEPART(yyyy,
v_UpdateInfo.DatePosted) AS varchar(255)) + '-' + RIGHT('0' + CAST(DATEPART(mm, v_UpdateInfo.DatePosted) AS VARCHAR(255)), 2)
AS MonthPosted, COUNT(1) AS Count
FROM v_UpdateComplianceStatus INNER JOIN
v_UpdateInfo ON v_UpdateComplianceStatus.CI_ID = v_UpdateInfo.CI_ID INNER JOIN
v_R_System ON v_UpdateComplianceStatus.ResourceID = v_R_System.ResourceID
inner join v_FullCollectionMembership fcm on v_UpdateComplianceStatus.ResourceID=fcm.ResourceID
WHERE (v_R_System.Operating_System_Name_and0 like '%Workstation 6.1%' and v_R_System.Obsolete0 = 0) AND (v_UpdateInfo.Severity IN (8, 10)) AND (v_UpdateInfo.IsSuperseded = 0) AND (v_UpdateInfo.IsEnabled = 1)
and fcm.CollectionID='ABC00328'
GROUP BY v_UpdateComplianceStatus.ResourceID, v_UpdateComplianceStatus.Status, CAST(DATEPART(yyyy,
v_UpdateInfo.DatePosted) AS varchar(255)) + '-' + RIGHT('0' + CAST(DATEPART(mm, v_UpdateInfo.DatePosted) AS VARCHAR(255)), 2))

But if I Put Alias (FF) then it is throwing a syntax error.

Answer 1

Too long for a comment. Here is your first snippet condensed into something readable. Note - learn to write and post readable code. You have gone with FAR too much line spacing, indentation, and white space for anyone to easily read your code. The harder it is to read, the harder it is to understand. I've done my best to condense your first query into the essential elements.

(
   SELECT blah blah,  
          CAST(DATEPART(yyyy, v_UpdateInfo.DatePosted) AS varchar(255)) + '-' + 
               RIGHT('0' + CAST(DATEPART(mm, v_UpdateInfo.DatePosted) AS VARCHAR(255)), 2) AS MonthPosted, 
          <aggregated column> 
    GROUP BY blah blah) as FF

where Status =2
Group By MonthPosted 
) as E

where E.MonthPosted = E.MonthPosted
order by MonthPosted Desc

So what do YOU see wrong here. The where clause is pointless - does nothing useful. You probably introduced that error with all the editing. And apparently you cast numbers to large strings for no reason. That is just sloppy. It is concerning that you feel a need to cast a number to zero-filled string in the first place - that is probably an inefficient approach. If you really need to do that, look up the documentation for convert. Style 112 does what you need - all you need to do is take the first 6 characters of the converted string. Note 6 characters, not 255 characters or MAX characters. That will declutter your code significantly.

And now that you have edited your post multiple times, it logically makes no sense. There is no "EE" alias in your first query at all - so the error you posted cannot come from that snippet. Most likely the problem comes from the code you left out.

So now it is time to divide and conquer - a technique you can use to build complicated queries. Focus on that snippet ONLY. Write it as a complete query and run it, test it, validate that it works. When it does execute without errors and returns the correct results (results that you have actually verified and not just glanced at to see if numbers/values look "reasonable"), you can then add additional logic as needed. Usually it is best to add joins 1 by 1 to avoid creating a monster problem that is difficult to understand and diagnose. Often the use of CTEs can help. Put your starting query in a cte, get it working correctly. Example:

with cte1 as (...)
select * from cte1 
order by ...;

Then add another cte to this first one and write it to use the first one, get it working. Example:

with cte1 as (...), 
cte2 as (select ... from cte1 inner join ...)
select * from cte2 
order by ...; 

Repeat that as needed. Once everything works you can try to bring it all together and "beautify" it if needed.

And start thinking about your code. Use the appropriate datatypes, do NOT try to prematurely optimize things, learn and understand your schema, and stop using tricks. As I mentioned, "select top 100 percent" is generally pointless. Rhetorical question - why do you think this is needed as a part of this derived table. And use meaningful alias names. "E" and "EE" are not meaningful. Remember that someone will need to maintain this code, perhaps even modify it. And, of course, create an alias for every table/view and use it. Something short (but not too short) but meaningful. This will vastly improve readability - especially with those very long view (presumably) names.

Lastly, You said "This query works fine if i run some part of it." That just is not a useful thing to write since it means nothing to the reader. Which part? All of it? The first line? Just lines 2 through 5? It is difficult to have a technical discussion - do not add confusion by using terms that are imprecise.