Get SQL query from user and run it against SQL Server

I want to develop very small application by C# which get some SQL query from user and execute it against specified SQL Server.

SQL Server and database must specified by user thus every things can change. My problem is user can enter various type of SQL queries, and every king of it should run in its own way.

For example

SELECT * FROM mytable

and

UPDATE mytable 
SET city = "NY" 
WHERE name = "tom"

can not execute in the same way.

I think I need to recognize user query type in my code, Is there any way to recognize it or any better way to run any possible query?