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Query Builder - Unique Records

altug_bayram

Hello ,

After quite a bit of personal struggle to solve my problem, I've decided to post it as a question to user and JMP community.

Have a database from which p1, p2, asset and time are pulled from. Database is an accumulating database which means parameters p1, and p2 are loaded as representing the last state for each asset at a specific time. In other words, prior older instances of p1 and p2 are invalid, and the most recent versions of p1 and p2 are needed for a given asset at the latest reported time.

Hence, what I need is an descending order via time and then force the outcome to be unique at asset level.

Any ideas of how I need to direct this in query builder ?

I rather prefer to have a solution by not using a custom SQL.... I actually have a solution at Custom SQL but I like to learn how to do this within query builder as I will be adding a few more pieces which be hard to do in the Custom SQL

Appreciate the help.

Altug Bayram

Accepted answers

Eric_Hill

DISTINCT won't help the OP, because there really aren't any distinct rows here.

I found a query that would solve the second case. I added 6 rows at the bottom that duplicate the max times for each asset, plus added an X variable. Here is the table:

And here is the query that works (it requires one subquery and one subquery within a subquery)):

The custom expression is:

t1.Time = (SELECT MAX(tInner.Time) FROM parts tInner WHERE t1.Asset = tInner.Asset)

AND

t1.X = (SELECT MAX(tInner.X) FROM parts tInner WHERE t1.Asset = tInner.Asset AND

tInner.Time = (SELECT MAX(tInner2.Time) FROM parts tInner2 WHERE tInner.Asset = tInner2.Asset))

I capitalized all the SQL keywords to make it easier to read. I tried some simpler queries, but they did not work.

HTH,

Eric

All comments

Bill_Worley

Hi Altug,

Please see the image below for getting a descending order for time.

Right click on your time variable in Available Columns and select "Order By" a new dialogue box will pop up in the lower right. From there you can pick the descending arrow to get the desired time order.

You could then use a filter with a prompt to select a unique asset level.

altug_bayram

Bill

Thanks for quick reply.

However, unless I am missing a critical thing here, this does not solve my problem.

1) Any asset's last valid point are typically not at the same time point, they are quite different. They can have years of difference.

2) I am not looking for a prompt solution if possible. I need this to be fully automated.

3) I am really not sure how "Filter By" with >= can make it unique either. I think you rather meant to filter by "="

So I need an approach that picks up the latest chronological entry for any asset without having to specify a time filter (cause the latest data can be anywhere in time).

Thanks.

Eric_Hill

Hey, altug,

Here is a table that I believe resembles what you are describing (but assume it is in a database rather than JMP):

My understand is that you would like to retrieve one row for A1, A2, A3, and A4 for which Time is the maximum. Is that correct?

I do not believe that is possible without doing a subquery that uses the MAX function, which you can do using a Custom Expression filter. Here is the query I ended up with:

In case that is too small to read, the custom expression is:

t1.Time = (select MAX(Time) from parts t2 where t1.Asset = t2.Asset)

So you pass in the value of Asset from the main query (t1.Asset) and select rows that have the maximum Time value for that asset.

Let me know if that helps.

Eric

altug_bayram

Hello Eric,

First thanks for your help ....

Your understanding is correct. I am just trying to pull a single row for each asset where Time is max (or most recent).

I applied your formulae. However, it is giving me an error.

I applied it as the real table name first and then as "t1"

t1.calendar_month = (select MAX(calendar_month) from my_table t2 where t1.engine_serial_num = t2.engine_serial_num)

t1.calendar_month = (select MAX(calendar_month) from t1 t2 where t1.engine_serial_num = t2.engine_serial_num)

ERROR : relation "my_table" does not exist.

ERROR while executing the query [ SQLSTATE: 42P01 ]

Eric_Hill

Hey, altug,

What database are you using?

Would you be willing to share the SQL from your Custom SQL query that gives you the result you are looking for?

Thanks,

Eric

Eric_Hill

My original example was for SQL Server, which is a little more forgiving. For Oracle, I had to format the table name in the subquery as schema.table, plus I had to quote my mixed case names:

t1."Time" = (select MAX(t2."Time") from SQBTEST."parts" t2 where t2."Asset" = t1."Asset")

Try changing my_table in your first attempt to <schema>.my_table and see if that helps.

Eric