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MySQL Max of 2 queries in a Union

Posted on 2014-09-04
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Last Modified: 2014-09-04
I have a MySQL query with 2 statements in a union - I want to get the MAX of both queries off of MaxOfStartTime giving 1 entry for each tool instead of for both. So if query 1 has the maxtime it shows query 1's result and if query 2 has the maxtime it shows query 2's result

(
SELECT SerializedAssets.SerialNumber, 
Max(JobDownholeEquipment.JobID) AS LastOfJobID, 
Max(JobDownholeEquipment.StartTime) AS MaxOfStartTime, 
'Job' AS JobType, Job.Company,Job.Rig,Job.RigNumber,Job.WellName,Job.City,Job.State
FROM SerializedAssets 
INNER JOIN JobDownholeEquipment ON SerializedAssets.SerialNumber = JobDownholeEquipment.ToolNumber
INNER JOIN Job ON Job.JobID = JobDownholeEquipment.JobID
GROUP BY SerializedAssets.SerialNumber
)
UNION
(

SELECT ToolAssemblies.ToolNumber, MAX(ToolAssemblies.Location) AS LastOfLocation, Max(ToolAssemblies.UploadTime) AS MaxOfUploadTime, 'Assembly' AS JobType,
"" AS Company,"" AS Rig,"" AS RigNumber,"" AS WellName,"" AS Cist,"" AS State
FROM ToolAssemblies
GROUP BY ToolAssemblies.ToolNumber
)

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Question by:r3nder
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3 Comments
 
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Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 40303737
I think I would create a view from your query, then apply the syntax suggestion for MySQL from this article I wrote: http://www.experts-exchange.com/Database/Miscellaneous/A_3203-DISTINCT-vs-GROUP-BY-and-why-does-it-not-work-for-my-query.html
hope this helps
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Author Comment

by:r3nder
ID: 40303767
ok how - I don't really have time to learn right now - I just need to figure  it out. In this particular scenario I have 1 record from each select statement that are the same tool number.
so the data looks like this
---------------------------------
1  | 12/12/2014  | Dallas
-----------------------------------
1  | 01/02/2009  | On job

and so on......
I need the max date of those records so that is displayed
-----------------------------------
1  | 12/12/2014  | Dallas
-----------------------------------
2  | 12/24/2014  | On Job

And so on
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LVL 6

Author Comment

by:r3nder
ID: 40303930
Fixed
 query += " DROP VIEW if exists v; ";
                query += " Create View v as ( ";
                query += " SELECT SerializedAssets.SerialNumber AS ToolNumber,  ";
                query += " Max(JobDownholeEquipment.JobID) AS LastOfLocation,  ";
                query += " Max(JobDownholeEquipment.StartTime) AS MaxOfUploadTime,  ";
                query += " 'Job' AS JobType, Job.Company,Job.Rig,Job.RigNumber,Job.WellName,Job.City,Job.State ";
                query += " FROM SerializedAssets  ";
                query += " INNER JOIN JobDownholeEquipment ON SerializedAssets.SerialNumber = JobDownholeEquipment.ToolNumber ";
                query += " INNER JOIN Job ON Job.JobID = JobDownholeEquipment.JobID ";
                query += " GROUP BY SerializedAssets.SerialNumber ";
                query += " ) ";
                query += " UNION ALL ";
                query += " ( ";
                query += " SELECT ToolAssemblies.ToolNumber AS ToolNumber, MAX(ToolAssemblies.Location) AS LastOfLocation, Max(ToolAssemblies.UploadTime) AS MaxOfUploadTime, 'Assembly' AS JobType, ";
                query += " '' AS Company,'' AS Rig,'' AS RigNumber,'' AS WellName,'' AS City,'' AS State ";
                query += " FROM ToolAssemblies ";
                query += " GROUP BY ToolAssemblies.ToolNumber, 'Assembly' ";
                query += " ) ";
                query += " Order by ToolNumber; ";
                query += " Select * From v Group by ToolNumber ";

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