SQL内部连接使用区分和按Desc排序

Question

table a. Table b . I have two tables. Table A has over 8000+ records and continues to grow with time. Table B has only 5 or so records and grows rarely but does grow sometimes.

I want to query Table A's last records where the Id for Table A matches for Table B. The problem is; I am getting all the rows from Table A. I just need the ones where Table A and B match once. These are unique Id's when a new row is inserted into table B and never get repeated.

Any help is most appreciated.

SELECT a.nshift, 
       a.loeeworkcellid, 
       b.loeeconfigworkcellid, 
       b.loeescheduleid, 
       b.sdescription, 
       b.sshortname 
FROM   oeeworkcell a 
       INNER JOIN dbo.oeeconfigworkcell b 
               ON a.loeeconfigworkcellid = b.loeeconfigworkcellid 
ORDER  BY a.loeeworkcellid DESC 

Answer 1

I am assuming you want to get the only the lastest (as you said) row from the TableA but JOIN giving you all the rows.You can use the Row_Number() to get the rownumber and then apply the join and filter it with the Where clause to select only the first row from the JOIN . So what you can try as below,

;WITH CTE 
AS
(
   SELECT * , ROW_NUMBER() OVER(PARTITION BY loeeconfigworkcellid  ORDER BY loeeworkcellid desc) AS Rn
   FROM oeeworkcell 
)


SELECT a.nshift, 
       a.loeeworkcellid, 
       b.loeecoonfigworkcellid, 
       b.loeescheduleid, 
       b.sdescription, 
       b.sshortname 
FROM   CTE a 
       INNER JOIN dbo.oeeconfigworkcell b 
               ON a.loeeconfigworkcellid = b.loeeconfigworkcellid 
WHERE
    a.Rn = 1

Answer 2

You need to group by your data and select only the data having the condition with min id.

SELECT a.nshift, 
       a.loeeworkcellid, 
       b.loeecoonfigworkcellid, 
       b.loeescheduleid, 
       b.sdescription, 
       b.sshortname 
FROM   oeeworkcell a 
INNER JOIN dbo.oeeconfigworkcell b 
ON a.loeeconfigworkcellid = b.loeeconfigworkcellid 
group by 
a.nshift, 
       a.loeeworkcellid, 
       b.loeecoonfigworkcellid, 
       b.loeescheduleid, 
       b.sdescription, 
       b.sshortname 
having a.loeeworkcellid = min(a.loeeworkcellid)