Basic question about Expression editor

[tanvirtonu]

I m a newbie in iReport.Can anybody pls tell me some basic thing about iReport Expression editor.

Assuming that I have three fields in my Db table

 

1.how to add the value of one field to another field and

show result in another field in ireport.

 

2.How to write a simple condition on a single field.

 

3.How to display the String-"No Data Found" in PK field of iReport,if no data is found.

 

4.how to use variable