vb.net database calculations 1

[ArthurPurdy]

Have a table in Access db called readings. My form has three text boxes. txtCurrent, txtPrevious and txtDifference. I need to put in the new reading. The difference between this input and the previous reading in the table needs to be outputed into txtDifference box.
How do I do this?
I usually program in vb6. trying to learn vb.net 2005.

Thanks in advance

 

[RonRepp]

txtDifference.Text=Val(txtCurrent.Text)-Val(txtPrevious.Text)


Ron Repp

If gray hair is a sign of wisdom, then I'm a genius.

 

[ArthurPurdy]

Thanks for that. What I need to know is.. In the batabase table there are 2 columbs. readings and usage. I need to know how to get the previuos reading into the txtprevious. once I enter the current reading, the calculation then takes place to give me the usage, and when I click save saves the current reading and the difference into usage in the database.

In vb6 I put the previous reading into a variable and use it later in the calc. I can't seem to get it right in vb.net 2005

The application is for our orphanage. I need to keep track of the electrical and water usage of 14 houses. The sponsors of the house need to know the usage.