Wait, what? I didn't get your point. You want to search for the content in a text file (.txt) using SQL database?
They are two different things with similar functionality, to store the data on file system. You use .txt files to store plain text (or HTML content if formatting is intended) and you use SQL database to store data in a well organized way (in a table form with rows and columns!) and compact way.
In any way, they are not interconnected to each other. A text file cannot search for content in database (impossible!) and database even with triggers and stored procedures is not able to search for the content inside the text file. However, using VB.NET you somehow can search for similar content in either a text file or the SQL database.
How to search specific string into text file from VB.NET[
^] (Text files)
How do i Search my record using Vb.net[
^] (Database)