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Editorial Team
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Asked: 2026-06-10T19:09:28+00:00

I have the following union query that queries for the most recent date of

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I have the following union query that queries for the most recent date of a column if it exists:

SELECT TOP 1 m.sentdate AS 'calltreelastsignedoff' 
FROM Incidents i 
INNER JOIN Plans p ON i.planuid = p.uid 
INNER JOIN IncidentMessages im ON i.uid = im.incidentuid 
INNER JOIN Messages m ON im.messageuid = m.uid 
WHERE p.uid = '031E3346-2921-426E-9494-1111111111' 
UNION
SELECT TOP 1 m.sentdate AS 'calltreelastsignedoff' 
FROM Incidents i
INNER JOIN PlanExercises pe ON i.planexerciseuid = pe.uid
INNER JOIN IncidentMessages im ON i.uid = im.incidentuid 
INNER JOIN Messages m ON im.messageuid = m.uid 
WHERE pe.planuid = '031E3346-2921-426E-9494-1111111111'

This will return 2 values if each query returns a top 1 result.

What I really want is to select the top 1 of the combined query.

How can I perform a select on the unioned query?

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1 Answer

  1. Editorial Team

    try this:

    You could do this with a derived table

    select top 1 from
(   
  SELECT TOP 1 m.sentdate AS 'calltreelastsignedoff' 
  FROM Incidents i 
  INNER JOIN Plans p ON i.planuid = p.uid 
  INNER JOIN IncidentMessages im ON i.uid = im.incidentuid 
  INNER JOIN Messages m ON im.messageuid = m.uid 
  WHERE p.uid = '031E3346-2921-426E-9494-1111111111' 

  UNION

  SELECT TOP 1 m.sentdate AS 'calltreelastsignedoff' 
  FROM Incidents i
  INNER JOIN PlanExercises pe ON i.planexerciseuid = pe.uid
  INNER JOIN IncidentMessages im ON i.uid = im.incidentuid 
  INNER JOIN Messages m ON im.messageuid = m.uid 
  WHERE pe.planuid = '031E3346-2921-426E-9494-1111111111' 
)a
order by <col>
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