SQL Script in HANA: Access row of table

Hi experts,

I have created the following table in my AMDP as below. I want to loop at the table and fetch the contents to fill the variables:

tab1 = SELECT mandt AS client,

                        col1 as Column1,

           col2 as Column2

           FROM DB_Table WHERE col1 = :input_parameter;

Now I want to implement the following logic:

If Column2 IS ' '      "Column2 returned from the query is BLANK

Then query again.

However I am not sure how to get the work area from the internal table tab1. Please help. Also I want to know how to set up a WHILE loop for the above scenario.

Regards,

Shalini