Restrict data entry based on another cell

Hi guys

I have a spreadsheet where I want to, for example, prevent a numerical entry into cell D7 if that entry would result in cell H7 becoming a negative value.
Is this possible and if so how is it done??
If it is possible and data entry is prevented, can the user then be prompted to enter a positive integer into cell C7 instead?

Checked google but cannot find a solution. Its possible I'm not using the correct terms in the search box

Thanks
northbank

Pl see the attached file.
D7 cell is validated to meet the conditions.

Originally Posted by kvsrinivasamurthy

Pl see the attached file.
D7 cell is validated to meet the conditions.

Thanks very much. great stuff.

Thanks for compliments.

Pl mark the thread SOLVED.