Select Records for Combo Box or List Box drop down

[LouPelagalli]

Hi,

This is actually two questions

1) What is the difference between a Combo Box or List Box?

2) Second, I would like to be selective about what is shown in the
Combo or List Box when used for data entry.

For Example
Table A Contains one column as follows:
Column 1
A1
A2
A3

Table B contains two columns as follows:
Colum 1 Column 2
A1 B1
A1 B2
A1 B3
A2 B4
A2 B5
A2 B6


Table C contains three columns, the first two reference back to table A
and B respectively for their valid values.

Table C, column 1 contains only values from Table A, column 1 as
selected from a Combo Box or List Box drop down.

I am able to get all this working so far, now my problem.

I'm entering a new record into table C, and column 1 contains the value
A2. But, my Combo Box or List Box drop down for column 2 which is
referencing Table B shows all values for A1 and A2.

How can I get my Combo Box or List Box drop down for Table C, column 2
to show me only values for what is contained in table C, column 1 -
which is from Table B where Column 1 = A2?

I hope this is clear.

Thank You in Advance for Your Help,

Lou