Java中的Pentaho Kettle程序按列合并多个csv文件

Question

I have two csv files employee.csv and loan.csv.

In employee.csv I have four columns ie empid(Integer),name(String),age(Integer),education(String).

In loan.csv I have three columns ie loan(Double),balance(Double),empid(Integer).

Now, I want to merge these two csv files into a single csv file by empid column.So in the result.csv file the columns should be,

• empid(Integer),
• name(String),
• age(Integer),
• education(String),
• loan(Double),
• balance(Double).

Also I have to achieve this only by using kettle api program in Java. Can anyone please help me?

Answer 1

First of all, you need to create a kettle transformation as below:

1. Take two "CSV Input Step", one for employee.csv and another for loan.csv
2. Hop the input to the "Stream Lookup" step and lookup using the "emplid"
3. Final step : Take a Text file output to generate a csv file output.

I have placed the ktr code in here .

Secondly , if you want to execute this transformation using Java, i suggest you read this blog. I have explained how to execute a .ktr/.kjb file using Java.

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Extra points:

If its required that the names of the csv files need to be passed as a parameter from the Java code, you can do that by adding the below code:

  trans.setParameterValue(parameterName, parameterValue);

where parameterName is the some variable name and parameterValue is the name of the file or the location.

I have already taken the files names as the parameter in the kettle code i have shared.

Hope it helps :)