ASP.NET

public -- database_BD GetDate()

public DateTime? GetDate()
{
    return db.database_BD.Select(d => d.UploadDate)
             .OrderByDescending(c => c)
             .FirstOrDefault();
}

public database_BD GetDate()
{
    var data = db.database_BD.Select(d => d.UploadDate)
                 .OrderByDescending(c => c)
                 .FirstOrDefault();
    
    return new database_BD { UploadDate = data };
}

public database_BD GetDate()
{
    return db.database_BD
             .OrderByDescending(d => d.UploadDate)
             .FirstOrDefault();
}

Quote:

f i click preview the data should be displayed.

From link[^]:

Basically, when you failed to connect to your SQL Server, the issue could be:
1) Network issue,
2) SQL Server configuration issue.
3) Firewall issue,
4) Client driver issue,
5) Application configuration issue.
6) Authentication and logon issue.

select count(*) from Table where username = 'Robert';DROP TABLE [Table];--'

// SqlConnection implements IDisposable, so wrap it in a "using" block:
using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["userConnectionString"].ConnectionString))
{
    cn.Open();
    
    // Use a parameterized query to avoid SQL injection:
    string sel = "select count(*) from [Table] where username = @username";
    
    // SqlCommand also implements IDisposable:
    using (SqlCommand com = new SqlCommand(sel, cn))
    {
        // Add the parameter to the command:
        com.Parameters.AddWithValue("@username", username.Text);
        
        int temp = Convert.ToInt32(com.ExecuteScalar());
        if (temp == 1)
        {
            Response.Write("User already exists..!!");
        }
    }
}