i have a doubt about the items that are inside of my comboBox?

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VB

SQL

I have a doubt, how can I select an identity that I am receiving from the database, inside my comboBox?

example:

table CARS

Mark | Model | Engine
BMW  |  M5   |   10
BMW  |  M3   |  123
BMW  |  M5   |  147

VW   | Golf  |  789
VW   | Fox   |   12
VW   |  CC   |  107

When I write txt_mark.text = "BMW" ... then
appears in the comboBox, all BMW model data: m5, m3 ...
and if I select one of them,in side of comboBox_Model,"M5", it should appear the following engine numbers: 10 and 174.

already tried this code :

select a.mark, a.model, a.Engine
from cars
where a.mark = ('"& txt_mark.text &"')

'(BMW)

'/ / this it will return, comboBox_model = "M5" and "M3" and if i select one of them the model "M5" or "M3" , and this will get all that there: 10, 123, 174 in cbx_Engine.
problem: if m5 then 10, 145 and not all....if m3 then 123  and not all..

select a.mark, a.model, a.Engine
from cars
where a.mark = ('"& txt_mark.text &"') and a.model = ('"& cbx_model.text &"')

'/ / this it will return, comboBox_model = "M5" and "M3" and the cbx_Engine nothing, empty.

Objective: When you select a comboBox_Model the items of the list, then will appear the  number of that model.

Can anyone show me another way ?
If you help me,I will appreciate.

With best regards,
Nillo123.