How to manipulate data from two data blocks? URGENT!

[Quoted] I'm using form 4.5.

[Quoted] I need to retrieve records in the following manner:

1. First pass. Retrieve all records from a table which do not exist in other table.
2. Second pass. Only pick those records with the following conditions:

. the tran_date in table A is less than the query date
      entered by the user.

    OR
    --
. the sum of table B + the sum of the table C
      is greater that the query amount entered by the user.

I have tried several solution, but no success. Such as, I want to retreive [Quoted] all records first in a temporary block. Then, loop through the block to insert data into another block. But Oracle complains taht the block is empty, I can't create any record in the block.

Any help?

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Best regards,