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Obtaining the primary key from an inserted DataSet to chain into other insertions

Suppose I have the following tables, in an Oracle DB
Foo:
+--------+---------+---------+
| id_foo | string1 | string2 |
+--------+---------+---------+
| 1 | foo | bar |
| 2 | baz | bat |
+--------+---------+---------+
Bar:
+--------+-----------+--------+
| id_bar | id_foo_fk | string |
+--------+-----------+--------+
| 1 | 1 | boo |
| 2 | 1 | bum |
+--------+-----------+--------+
When I insert into Foo, by using a Dataset and JDBC, such as
Dataset<Row> fooDataset = //Dataset is initialized
fooDataset.write().mode(SaveMode.Append).jdbc(url, table, properties)
an ID is auto-generated by the database. Now when I need to save Bar, using the same strategy, I want to be able to link it to Foo, via id_foo_fk.
I looked into some possibilities, such as using monotonically_increasing_id() as suggested in this question, but it won't solve the issue, as I need the ID generated by the database. I tried what was suggested in this question, but it leads to the same issue, of unique non-database IDs
It's also not possible to select from the JDBC again, as string1 and string2 may not be unique. Nor is it possible to change the database. For instance, I can't change it to be UUID, and I can't add a trigger for it. It's a legacy database that we can only use
How can I achieve this? Is this possible with Apache Spark?

I'm not a Java specialist so you will have to look into the database layer on how to proceed exactly but there are 3 ways you can do this:
You can create a store procedure if the database server you are using is capable of (most do) and call it from your code.
Create a trigger that returns the id number on the first insertion and use it in your next DB insertion.
Use UUID and use this as the key instead of the database auto generated key.

How to use nested Scenario Outline in Cucumber java

2suppose i have a Scenario Outline like
#Scenario1
Scenario Outline:Scenario one
Given fill up login fields "<email>" and "<password>"
And click the login button
Examples:
| email | password |
| someEmailAddress | SomePassword |
| someEmailAddress2| SomePassword2 |
and another Scenario like
#Scenario2
Scenario Outline:Scenario two
Given fill up fields "<value1>" and "<value2>"
Examples:
| value1 | value2 |
| value11 | value21 |
| value12 | value22 |
How could i run scenario like login with 'someEmailAddress' and fill up with all scenario2 value and then login with 'someEmailAddress2' and do the same.

Cucumber scenarios are tools we use to describe behaviour i.e. what is happening and why its important. They are not tools to program tests. The way to use Cucumber effectively is to keep your scenarios simple, and let code called by step definitions do your programming for you.
Step definitions and the methods they call are written in a programming language. This gives you all the power you need to deal with the details of how you interact with your system.
The art of writing Cucumber scenarios is for each one to talk about
The state we need setup so we can do something (Givens)
Our interaction (When)
What we expect to see after our interaction. (Then)
So for your scenario we have
Scenario: Login
Given I am registered
When I login
Then I should be logged in
When we make this scenario work our program has the behaviour that we can login. So then we can use that behaviour in other scenarios e.g.
Scenario: See my profile
Given I am logged in
When I view my profile
Then I should see my profile
Now to make this work we might need a bit more work because this scenario doesn't have a registered user yet. We can deal with this in a number of ways
1) Add another Given, perhaps in a background
Background:
Given I am registered
Scenario ...
Given I am logged in
2) We can register in the login step e.g.
Given "I am logged in" do
#i = register_user
login_as user: #i
end
Notice how in this step we are calling helper methods register_user and login_as to do the work for us.
This is the way to start using Cucumber. Notice how my scenarios have no mention of how we login, no email, no password, no filling in anything. To use Cucumber effectively you have to push these details down into the step definitions and the helper methods they call.
Summary
Keep you scenarios simple and use them to describe WHAT and explain WHY. Use the step definitions and helper methods to deal with HOW. There is no need to use Scenario Outlines when using Cucumber and you should never be nesting them.

There is no support for nested scenario outline in cucumber. but you can use following way to overcome it.
Scenario Outline:Scenario one and two
Given fill up login fields "<email>" and "<password>"
And click the login button
And fill up fields "<value1>" and "<value2>"
Examples:
| email | password | value1 | value2 |
| someEmailAddress | SomePassword | value11 | value21 |
| someEmailAddress | SomePassword | value12 | value22 |
| someEmailAddress2| SomePassword2 | value11 | value21 |
| someEmailAddress2| SomePassword2 | value12 | value22 |

Java Database Access Builder Patter

I have a database with a table called Car. The car table looks like this:
+----+------+--------------+-----------+----------+------+
| Id | Name | Desccription | Make | Model | Year |
+----+------+--------------+-----------+----------+------+
| 1 | A | something1 | Ford | Explorer | 2010 |
| 2 | B | something2 | Nissan | Ultima | 2005 |
| 3 | C | something3 | Chevrolet | Malibu | 2012 |
+----+------+--------------+-----------+----------+------+
Different pages on my website want to display different information. Some pages only want to display the name, others wants to display the make and model, etc.
I have an api that the web calls to retrieve all this information. The api uses JPA and QueryDSL to communicate with the database and fetch information. I want to only fetch the information that I want for that particular page. I'm thinking about implementing some sort of builder patter to my repo to allow for me to only retrieve what I want but I'm not quite sure how to go about it.
For example, my home page only wants to display the Name of the car. So it'll call the HomeController and the controller will call the HomeService which will call the repository layer something like this:
carRepository.getCarById(1).withName().build();
Some other page that wants to display the make and model would make a repo call like this:
carRepository.getCarById(1).withMake().withModel.build();
What is the best way to implement something like this in Java/Jpa?

If I understand the question correctly, you want queries for different projections of your entities to be built dynamically.
In that case, dynamic entity graphs are what you want (see e.g. here: https://www.thoughts-on-java.org/jpa-21-entity-graph-part-2-define/). You start with an empty entity graph, and each call to one of your with() method simply adds a field to the graph.
The base query remains unchanged, you just need to set the fetch graph hint (javax.persistence.fetchgraph) upon calling build() (note that the samples in the above link use load graphs instead of fetch graphs; the subtle difference between the two is described here: What is the diffenece between FETCH and LOAD for Entity graph of JPA?)

ESPER - CEP trying to find the max(value) form events

Hello I'm desperate trying to find a way in ESPER - CEP to output the events that have the max value. Here's a good example to illustrate my problem:
| value | category | date |
| 12.2 | A | yyyy-MM-dd HH:mm:ss |
| 13.3 | A | yyyy-MM-dd HH:mm:ss |
I want the following output:
| value | category | date |
| 13.3 | A | yyyy-MM-dd HH:mm:ss |
Very basic in SQL : select max(value), category date from tab group by category
Now in Esper, i have tried many things: output every, output last, contexts.. But couldn't find a solution :/ It either outputs nothing or outputs all the lines. With "output first every", it only ouputs the first line, regardless of the max() comparison.
Is there someone who has an idea of how to proceed to obtain the max(value) and group by a parameter from a stream?
Thanks for your help :)

Doc link for controlling time keeping: http://esper.codehaus.org/esper-5.1.0/doc/reference/en-US/html_single/index.html#api-controlling-time

Jasper Reports - Limit number of rows in a group

I have a CSV datasource something like this:
User,Site,Requests
user01,www.facebook.com,54220
user01,plusone.google.com,2015
user01,www.twitter.com,33564
user01,www.linkedin.com,54220
user01,weibo.com,2015
user02,www.twitter.com,33564
user03,www.facebook.com,54220
user03,plusone.google.com,2015
user03,www.twitter.com,33564
In the report I want to display the first 3 rows (max) for each user, while the other rows will only contribute to the group total. How do I limit the report to only print 3 rows per group?
e.g
User Site Requests
user01 | www.facebook.com | 54220
plusone.google.com | 2015
www.twitter.com | 33564
| 146034
user02 | www.twitter.com | 33564
| 33564
user03 | www.facebook.com | 54220
user03 | plusone.google.com | 2015
user03 | www.twitter.com | 33564
| 89799
It is really just the line limiting I am struggling with, the rest is working just fine.

I found a way to do it, if anyone can come up with a more elegant answer I would be happy to see it, as this feels a bit hacky!
for each item in detail band:
<reportElement... isRemoveLineWhenBlank="true">
<printWhenExpression><![CDATA[$V{userGroup_COUNT} < 4]]></printWhenExpression>
</reportElement>
where userGroup is the field I am grouping by. I only seemed to need the isRemoveLineWhenBlank attribute for the first element.

you may consider to use subreport by querying the grouping fields in the main report and then passing the grouping fields as parameters into the subreport; the merits of this method is to avoid the report engine to actually looping through all un-required rows (although they are not shown) and spending unnecessary server-to-server or server-to-client bandwidth especially when the dataset returned is large