FileMaker, internally, is not a SQL based engine. FileMaker's Draco engine does, howevever, support a SQL-92 implementation of a SQL to Native FileMaker query translation which allows for SQL based interaction.
FileMaker's own ExecuteSQL function currently only allows for the execution of SELECT statements with the ability to read data from FileMaker's database. The implementation of SQL, however, extends to the full CRUD capabilities and is most commonly accessed via a plug-in provider. That is, unless a developer is able to write their own plug-in for taking advantage of FileMaker's SQL API.
The following is a list of useful resources related to using SQL within FileMaker.
@todo - complete this section.