Unlike C# API, which allows you to automatically keep your cache and SQL server consistent using read-through and write-through policies, the SQL API works only with data already loaded to the cache. In other words, the data updates you do with Ignite SQL are not automatically written to the SQL server and the SELECTs will not automatically load missing data from the SQL Server.
Ignite has Native Persistence <https://apacheignite.readme.io/docs/distributed-persistent-store> feature where persistence is transparent to any API including SQL but that means you will have to replace SQL Server persistence with native persistence. Having both SQL Server and native persistence does not provide consistency guarantees.
