You will need to perform any filtering in your query outside of the Combo Box. The object is designed only to show the results of a direct query to a column in a table.
In order to do what you are suggesting, I recommend querying the database and putting the result into a text file, an intermediate database that the Combo Box can access, or into a string tag array. If you are a sophisticated SQL programmer, you can write the entire query into the connection string, or use a string tag to contain the connection string, however in any event you will need to create a new query for the database whenever you want to change the display list in the combo box.
There are a variety of sample applications using various techniques in InduSoft Web Studio to create queries and return results in the Sample Applications. For instance, the application called "Database" uses ADO objects to create the connection in VB. Additionally, this blog discusses how to create intermediate data (for a text report) using a SQL Cursor. The output of the cursor could be used to populate a text file or a tag array for your Combo Box. http://www.indusoft.com/blog/2014/0...-database/
Here is a blog about using an ad hoc query to access data in a database that might also be helpful. It has a sample application that may be useful to see how it is done. http://www.indusoft.com/blog/2013/0...eb-studio/
Finally here is a blog and a sample application discussing how to get data from and back into a .csv (text) file that could be also useful for getting the aggregated list of values for your combo box. http://www.indusoft.com/blog/2013/0...b-studio/.
I hope that you find this information useful. Also you can search the Corporate blogs and forums for more information (open the web pages of the blogs or the forums before entering your search strings so that the search will be pertinent to the blogs or the forms respectively) and also don't forget about our online training videos that discuss using and demonstrating the various InduSoft Web Studio functionalities. http://www.indusoft.com/Training/On...ing-Videos
This may assist you in finding the best way to find an efficient solution for your problem.