How to make multiple qualifying DropDownList for SQL search in ASP.NET?

Question

JavaScript

A simple example, but the implementation doesn't reach me. There is one DropDownList (DDL1) receiving values ​​from SQL.
If you select one of the values, SQL is asked to look for that value/word, or rows that contain similar words.
The second one (DDL2) appears, showing the values ​​from the search results. For example, an SQL table contains the following values:
|Column1_____|Column2______|Column3|
|1______________|2______________|3_________|
|1______________|0______________|0_________|
|a______________|b______________|c_________|
In the first list, select "1", there is a search in the first column. A second list appears in which the values ​​correspond to the search in the table - "2" and "0". We select "2", the third one (DDL3) appears with the value "
Here is such a clarifying search-filter-selector. Searched but didn't find anything similar. It seems that JS is indispensable here

Answer 1

Select, How to display the information of the second select from the selection of the first?