Need to select only the first row of each unique value

ROW_NUMBER is your friend.  You can use:

ROW_NUMBER OVER (PARTITION BY BA_VIEW_SHIPPING_ORDERS.SM_NUMBER,AUDIT_TRAIL.SOURCE_AK ORDER BY VIEW_SM_STOCK.STM_AUTO_KEY DESC) 

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(or in PARTITION BY, whatever distinguishes them), and then select only results where that value is = 1.

What makes it the "lowest" record? Is it because it's the "highest" STM_AUTO_KEY? if that's the case, then Dustin Saunders has your answer.

I'm sorry, I typo'd in my post.  ROW_NUMBER is a method and needs parenthesis ->  ROW_NUMBER()

ROW_NUMBER() OVER (PARTITION BY BA_VIEW_SHIPPING_ORDERS.SM_NUMBER,AUDIT_TRAIL.SOURCE_AK ORDER BY VIEW_SM_STOCK.STM_AUTO_KEY DESC) AS "RN"

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You can add that into the Query where you have it now, and do something like:

;WITH result AS (
 <your whole current query>
)
SELECT * FROM result
WHERE RN=1

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>> Sorry, that was silly of me.

Absolutely not at all silly, and definitely no need to apologise....

It is our role as Experts to explain in such a way that you do understand / can use the suggestions.

Just to clarify Dustin's solution :

; with CTE as 
(  SELECT -- DISTINCT   -- dont think you need this if we are selecting by RN 
                         dbo.AUDIT_TRAIL.SOURCE_TABLE, dbo.AUDIT_TRAIL.SOURCE_AK, dbo.AUDIT_TRAIL.SOURCE_FIELD, dbo.AUDIT_TRAIL.ORIG_VALUE, 
                         dbo.AUDIT_TRAIL.NEW_VALUE, dbo.BA_VIEW_SHIPPING_ORDERS.ENTRY_DATE AS SHIP_ENTRY_DATE, dbo.AUDIT_TRAIL.STAMPTIME, 
                         dbo.BA_VIEW_SHIPPING_ORDERS.SM_NUMBER, dbo.SYS_USERS.USER_NAME, dbo.SYS_USERS.FIRST_NAME, dbo.SYS_USERS.LAST_NAME, 
                         dbo.VIEW_SM_STOCK.STM_AUTO_KEY, dbo.VIEW_SM_STOCK.QTY_RESERVED, dbo.VIEW_SM_STOCK.QTY_SHIPPED, dbo.VIEW_SM_STOCK.STOCK_LINE, 
                         dbo.VIEW_SM_STOCK.CONDITION_CODE, dbo.VIEW_SM_STOCK.WAREHOUSE_CODE, dbo.VIEW_SM_STOCK.ORIG_WAREHOUSE_CODE, 
                         dbo.VIEW_SM_STOCK.LOCATION_CODE, dbo.VIEW_SM_STOCK.SERIAL_NUMBER, dbo.SYS_USERS.EMPLOYEE_CODE,
ROW_NUMBER() OVER (PARTITION BY BA_VIEW_SHIPPING_ORDERS.SM_NUMBER,AUDIT_TRAIL.SOURCE_AK ORDER BY VIEW_SM_STOCK.STM_AUTO_KEY ) AS RN  
-- DESC in the 'order by' means descending sequence to get the highest first. I dont think that is what you are asking for - so leave it out for ASC (ascending = low to high) sequence....
  FROM            dbo.VIEW_SM_STOCK RIGHT OUTER JOIN
                         dbo.BA_VIEW_SHIPPING_ORDERS ON dbo.VIEW_SM_STOCK.SMD_AUTO_KEY = dbo.BA_VIEW_SHIPPING_ORDERS.SMD_AUTO_KEY LEFT OUTER JOIN
                         dbo.AUDIT_TRAIL LEFT OUTER JOIN
                         dbo.SYS_USERS ON dbo.AUDIT_TRAIL.SYSUR_AUTO_KEY = dbo.SYS_USERS.SYSUR_AUTO_KEY ON 
                         dbo.BA_VIEW_SHIPPING_ORDERS.SMH_AUTO_KEY = dbo.AUDIT_TRAIL.SOURCE_AK
  WHERE        (dbo.AUDIT_TRAIL.SOURCE_TABLE = 'SMH') AND (dbo.AUDIT_TRAIL.ORIG_VALUE = 'PICKING') AND (dbo.AUDIT_TRAIL.NEW_VALUE = 'PACKING')
  GROUP BY dbo.AUDIT_TRAIL.SOURCE_AK, dbo.VIEW_SM_STOCK.STM_AUTO_KEY, dbo.AUDIT_TRAIL.SOURCE_TABLE, dbo.AUDIT_TRAIL.SOURCE_FIELD, dbo.AUDIT_TRAIL.ORIG_VALUE, 
                         dbo.AUDIT_TRAIL.NEW_VALUE, dbo.BA_VIEW_SHIPPING_ORDERS.ENTRY_DATE, dbo.AUDIT_TRAIL.STAMPTIME, dbo.BA_VIEW_SHIPPING_ORDERS.SM_NUMBER, 
                         dbo.SYS_USERS.USER_NAME, dbo.SYS_USERS.FIRST_NAME, dbo.SYS_USERS.LAST_NAME, 
                         dbo.VIEW_SM_STOCK.QTY_RESERVED, dbo.VIEW_SM_STOCK.QTY_SHIPPED, dbo.VIEW_SM_STOCK.STOCK_LINE, dbo.VIEW_SM_STOCK.CONDITION_CODE, 
                         dbo.VIEW_SM_STOCK.WAREHOUSE_CODE, dbo.VIEW_SM_STOCK.ORIG_WAREHOUSE_CODE, dbo.VIEW_SM_STOCK.LOCATION_CODE, 
                         dbo.VIEW_SM_STOCK.SERIAL_NUMBER, dbo.SYS_USERS.EMPLOYEE_CODE
--ORDER BY SOURCE_AK
) SELECT * 
  FROM CTE 
  WHERE RN = 1
  ORDER BY SOURCE_AK

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Which is pretty much the same in your other question....  https://www.experts-exchange.com/questions/29121813/Error-when-using-ROW-COUNT-alias-in-where-clause.html


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