you have 2 error
1) use user name of your pc b4 the servername
error
Data Source=.\\SQLExpress;Initial
ans
Data Source=PC Username\\SQLExpress;Initial
cos (.) only work with Sql 2000
2) use @ b4 connection string
SqlConnection conn = new SqlConnection(@"Data Source=.\\SQLExpress;Initial Catalog=Food;Integrated Security=SSPI;");
And the Final Connection string will
SqlConnection conn = new SqlConnection(@"Data Source=PC Username\\SQLExpress;Initial Catalog=Food;Integrated Security=SSPI;");