Return Value
For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. For all other types of statements, the return value is -1.
You can use ExecuteNonQuery method to perform catalog operations (for example, querying the structure of a database or creating database objects such as tables); or to change the data in a database, without using a DataSet, by executing UPDATE, INSERT, or DELETE statements.
Although ExecuteNonQuery does not return any rows, any output parameters or return values mapped to parameters are populated with data.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2