Checkboxes are a special type of input. Whatever is present for the value attribute in the checkbox is what you will see inserted into your db, but only if the box is checked, if it is not checked there will be no value for that form element.
You can insert and update with checkboxes by using the regular DataAssist Insert and Update server behaviors. Since you can put any value into the checkbox the data type of the column will depend on what values you want the checkboxes to have. So if you are setting a checkbox to a string value like "test" then you would want to have a varchar type column in your db for this checkbox.