Help combo box

Hello,

I have a problem and I do not know how to fix it maybe you can give me a hand ....

then I try to be clear:

I have a combo box which is connected to a database. Entering the first few letters of a word I could make a filter (because the data are many) and then as for the t9 phone, typing "a" I filter all the records in the database and I found only the records that begin with " a ". So far everything is okay.

The problem is that in order to display all the records filtered by force must click on the arrow of the combo box.

What we want it to automatically where you enter the letter or letters in order to filter the databaase the combo box should open by itself so as to show me all results.

You can do this?

Thanks for possible help