Understanding Big Data

The Dataconomy Team published a book for beginners https://www.smashwords.com/books/view/498197. The title is Unserstanding Big Data.
They have also a news and job portal in the topic. 

You can get this book as a gift if you take part in this survey: https://ftjournal.typeform.com/to/FFYCuk 

I've just downloaded, it seems to be an overview, maybe useful for managers with some use case. good luck.

Using rownum and order-by

If you try to use rownum and order-by in a select statement, maybe the result will not match with your expectation. It is because the order-by is one of the last operation in the queue.

Using rownum function

The query:
SELECT ROWNUM,
       T.DOMA_KY,

       T.SHORT_DESCRIPTION_LB

  FROM T_DOMAIN T
 WHERE T.ACRONYM_CD = 'PLCY'
 ORDER BY T.DOMA_KY

	ROWNUM	DOMA_KY	SHORT_DESCRIPTION_LB
1	6	261	P1-Jobs, Growth and Investment
2	2	262	P2-Digital Single Market
3	4	263	P3-Energy Union and Climate
4	8	264	P4-Internal Market
5	3	265	P5-Economic and Monetary Union
6	10	266	P6-EU-US Free Trade
7	7	267	P7-Justice and Fundamental Rights
8	9	268	P8-Migration
9	5	269	P9-EU as Global Actor
10	1	270	P10-Democratic Change

Using row_number() function

The query:
SELECT ROW_NUMBER() OVER (ORDER BY T.DOMA_KY) ROW_NUMBER,
       T.DOMA_KY,
       T.SHORT_DESCRIPTION_LB,
       T.ROWID
  FROM T_DOMAIN T
 WHERE T.ACRONYM_CD = 'PLCY'
 ORDER BY T.DOMA_KY

	ROW_NUMBER	DOMA_KY	SHORT_DESCRIPTION_LB
1	1	261	P1-Jobs, Growth and Investment
2	2	262	P2-Digital Single Market
3	3	263	P3-Energy Union and Climate
4	4	264	P4-Internal Market
5	5	265	P5-Economic and Monetary Union
6	6	266	P6-EU-US Free Trade
7	7	267	P7-Justice and Fundamental Rights
8	8	268	P8-Migration
9	9	269	P9-EU as Global Actor
10	10	270	P10-Democratic Change

Force java project import to Eclipse

There are several way to import an existing code, folder as a java project to Eclipse.

These are very useful solutions if your project is built by not maven:

• create a new Eclipse project with a same source folder. Sometimes you get an overlapping error.
• create a new Eclipse project from an existing ant build file. Specially the Eclipse try to parse and figure out which ant target is the best to compile your project during the import. Unfortunately the Eclipse try to find "javac" ant calls in your build script.
• try import only the java folders of the projects
• try to import as an existing project, and maybe the Eclipse will recognize
• create a .project file and enjoy

to create a .project file is very easy, you can copy an old one. Or create a file like this:

<?xml version="1.0" encoding="UTF-8"?>

<projectDescription>

<name>Pecunia</name>

<comment></comment>

<projects>

</projects>

<buildSpec>

</buildSpec>

<natures>

</natures>

</projectDescription>

Create a design for WebServices

I tried to find a really easy and good tool to create a design for Web-services.

Maybe I  did not spend enough time to find one, so I chose again my favorite yEd.

The yEd is a very lightweight and useful application for drawing, creating boxes with attributes, relations, colors, grouping.

The artifact of the yEd is an XML. It is very easy to modify, to maintain, to load it to the repository.

So you can create Entities with this tool, just drop it from the Entity relationship part of the Palette. You can add attributes, and you can also define relations.

What is the benefit to have a web-service design?

Firstly, you will have a documentation. You can share the current functionality, the entities. If you leave the project, the newcomer colleague can use it.

Secondly you has an overview. It is not easy to follow the XML files, where the WS is defined, and also not easy to parse the java objects, where the annotations are, which filed is the part of the XML element.

Thirdly you get a review. I found with my little WS two little thing, when it was modified, the coder forgot to follow the naming conventions. After that I found a bug in the Java objects, in the annotations. The sub entity name was different in the Entity java class, and in the parent java class. Despite of this bug the WS also worked.

An example:

Rename maven projects in the Eclipse

I am working on old project, with old code. The problem is, if you want to import the full maven project hierarchy you will be faced a name conflict.

It is not a big issue, but you can not import the two project in same time.

What is the logic to give the project name in the Eclipse?

The Eclipse use the folder name for the root project, and the Artifact Id for the children maven projects.

The solution

There is a solution in the Eclipse, when you stat the import with the wizard, you can select a predefined template to rename the Eclipse project name. You can find it under the advanced label in the first step of the wizard.

Let's start a blog

Let's start a blog, just to keep in mind my daily IT challenges. If it will be successful, I will increase my English and I will have a good collection of solutions IT problems.

If you would like to help me, welcome!

When I start this blog I have more than 15 years experience in IT development, consultancy and design.

You can find here solution with Java, Oracle, JavaScript, ANT, MAVEN, Shell, Perl, Regexp, XML, RSS, REST, PL/SQL etc.