The SQL search engine is kept in the system for backward compatibility with older versions and for attachment searching. It uses standard SQL queries to search for the given expression. It runs a separate query for each document type. You can find the search query for a document type at Site Manager -> Development -> Document types -> ... select document type ... -> Queries -> Edit () the searchtree query.
Common fields (such as document name) are searched using the cms.root.searchdocuments query.
Uploaded files are searched using the cms.root.searchattachments query. If you want to search uploaded files, you need to configure the system as described in the Installation and deployment -> Additional configuration tasks -> Configuration of full-text search in files topic. In this case, the files are searched using the Microsoft SQL Server Search Engine.
The search dialog can be easily integrated into the website using the web parts in the Full-text search category (SQL search dialog, SQL search box, etc.) or using the CMSSearchDialog and CMSSearchResults server controls (in your ASP.NET code).
You can exclude document types by setting the Exclude document types from SQL search value in the Site Manager -> Settings -> System -> Search dialog. You need to enter the code name, such as cms.article. You can enter multiple document types separated with a semicolon (;).
You can exclude website sections from search by setting the Exclude documents from SQL search in the Site Manager -> Settings -> System -> Settings dialog. You need to enter the alias path of the section that should be excluded. A single document can be excluded using e.g. /news/news1, whole website section can be excluded using e.g. /news/%. You can enter multiple values separated by semicolons (;).
The Exclude this document from search property of individual documents can also be used to exclude them from SQL search. This property can be configured by selecting a document from the content tree in CMS Desk and going to Content -> Edit -> Properties -> General.
If you only need do modify the search results format, you can do that by modifying the transformation searchresults in Site Manager -> Development -> Document Types -> edit () Root -> Transformations.
If you need to integrate a custom search engine or make additional modifications to the search results returned by the standard search engine, you can develop your own search provider. You can find more details in the API programming and Kentico CMS internals-> Custom providers -> Custom Search Provider topic.