C#

I have 2 projects in 1 solution. Where one of the project is included with a database manager class.

Projects

Then the second project is included with another class which have all properties of the form. That class is called Diseases class. I want store different types of diseases. Here I set the options of the input like only numbers or can't leave empty and so on.

Properties

I would to insert data from the form throw the properties class but can't see the properties class. I have a following error message:

The type or namespace name 'Diseases' could not be found (are you missing a using directive or an assembly reference?)

I'm lost. Anybody can help me please what I doing wrong?

1. The #IF symbols are ALL OVER THE CODE. It's a mess.
2. There are multiple project files that simply exist to compile different logic paths based on the symbol.

We are calling 2 methods using TPL
both methods return similar data type <string>

Task.WhenAll  returns a string array.

What is the best place to await.

Line 3 pattern
or
Line 4 + 5 pattern
or
Line 6 + 7 pattern

What is the reason for choosing one over the other pattern?
Appreciate any help.
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1. Task<string> t1 = SomeMethod_A_ToCallStoredProcedure();
2. Task<string> t2 = SomeMethod_B_ToCallStoredProcedure();;


3. string[] X = await Task.WhenAll(t1,t2);


4. string[] X = Task.WhenAll(t1,t2)
5. await X;

6. string[] X = Task.WhenAll(t1,t2)
7. X.wait;

Windows Forms project. Panel is 1800 x 900 with a background image. Why is the image dark? I tried other images and they display correctly. I played around with settings and no luck. The second image is the original.

public DataSet ExecuteQuery()
      {
          // construct an empty result database to return

          DataTable table = ds.Tables["Fill_Data"];
          //DataTable table = ds.Tables[0];
          // Presuming the DataTable has a column named Date.
          string expression;
         //expression = "40Percent <" + lblTA.Text.ToString();
         expression = "40Percent = 0.355";

          DataRow[] foundRows;

         // Use the Select method to find all rows matching the filter.
         foundRows = table.Select(expression);

         // Print column 0 of each returned row.
         for (int i = 0; i < foundRows.Length; i++)
         {
             Console.WriteLine(foundRows[i][0]);
         }

         return ds;
      }