The Command Object in ADO.NET executes SQL statements and Stored Procedures against the data source specified in the Connection Object. The Command Object required an instance of a Connection Object for executing the SQL statements. That is, for retrieving data or execute an SQL statement against a Data Source , you have to create a Connection Object and open a connection to the Data Source, and assign the open connection to the connection property of the Command Object. When the Command Object return result set , a Data Reader is used to retrieve the result set.
The Command Object has a property called CommandText, which contains a String value that represents the command that will be executed in the Data Source. When the CommandType property is set to StoredProcedure, the CommandText property should be set to the name of the stored procedure.
Click the following links to see some important built in methods uses in the Command Object to execute the SQL statements.