Before I try to summarize, please be aware of the full Clover documentation that can be found here.
Let's illustrate a parameter with the following simple example :
"I only want to load customers from a specific country and export those customers to a file that I can give to a sales rep".
The best way of dealing with this is to define a parameter that can be altered each time you want to run your graph. You simply set the parameter to the country before you run it.
What types of Parameters are there
|•||Internal : this is defined as a part of the Graph. You simply set up a parameter in the Parameters section of the Outline panel, bottom left. This can only be seen by the graph it is defined within.|
|•||External : this is basically a file that contains the parameters and being a file it can be shared by more than one graph|
|•||Parameters passed in via an HTTP call : this is dealt with in the Advanced section of the QSG. If you are serving up integration functionality remotely, you will often want to pass in a parameter. A lookup, for example, may want to return a list of Customer beginning with the letters passed in as a parameter. This functionality required the Clover ETL Server.|
This Video shows us generating a country specific export file which is parameter driven.