Why does a create database statement return values when called from C#?

I have the following database command: CREATE DATABASE [test1] ON (FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\test1.mdf'), (FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\test1_log.ldf') FOR ATTACH When I do it via C# it returns me more than one value. Here is the C# code: public void RunQuery(string query, bool longRunning = false) { using (var cmd = new SqlCommand(query, Connection)) { cmd.CommandTimeout = longRunning ? _longRunningCommandTimeout : _commandTimeout; cmd.ExecuteNonQuery(); } } This results in the following error from SQL Server: > Error: Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, , >= or when the subquery is used as an expression.
The statement has been terminated And here is the stack trace from the exception: at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() The database attach succeeds, even though an error is raised. When I execute the same query (under the same user) via Management Studio it gets me just the following: > Commands completed successfully. Is it possible that the CREATE DATABASE statement returns more than one result?