ASP.NET C＃不检查数据库中是否存在用户

Question

I create an if else statement to check whether a database exists in DB, but ASP does not check it?

I think I am doing this wrong.

This is my code...

 SqlCommand check = new SqlCommand("SELECT Count(*) FROM [Users] WHERE Username='" + @username + "'", Connect);

        int exist = check.ExecuteNonQuery();

        if (exist > 0)
        {
            txtuser.Text = "User already exists";
        } else 
        // Insert the non-existing data to database

Answer 1

Try like tthis...

int exist =(int) check.ExecuteScalar()

ExecuteNonQuery() returns the number of rows affected in database.But here you are not updating or inserting so it will return 0 always.