What is the difference between 1 column linq result and more than 1 column linq result

Question

This behavior make me crazy since I could not find a logical explanation of why ????

All I want to do is 2 things
1- Columns Count in Linq result
2- Columns Name in Linq Result

The STRANGE problem is, if my linq result is more than 1 column, it worked, if it 1 column it did not

Dim query_3_col = From t In db.Customers Select t.CustomerID,t.City,t.Address
        Dim col_count_3_col As Integer
        col_count_3_col = query_3_col.ToArray(0).GetType.GetProperties().Count ' col_count_3_col = 3 <-- correct
                          
        Dim query_3_col_first = query_3_col.First()
        Dim prop_3_col = (from propertyy in query_3_col_first.GetType().GetProperties()
                        select propertyy.Name).ToList()
        For Each item In prop_3_col
            Debug.Print(item.ToString)
            ' I am getting CustomerID,City,Address <-- correct
        Next

        col_count_3_col = prop_3_col.Count ' col_count_3_col = 3 <-- correct

Let do the above again with 1 column result

        Dim query_1_col = From t In db.Customers Select t.CustomerID
                          
        Dim col_count_1_col = query_1_col.ToArray(0).GetType.GetProperties().Count ' col_count_1_col = 2 <-- WRONG

        Dim query_1_col_first = query_1_col.First()

        Dim prop_1_col = (from propertyy in query_1_col_first.GetType().GetProperties()
                        select propertyy.Name).ToList()
        
        For Each item In prop_1_col
            Debug.Print(item.ToString)
            ' I am getting Chars,Length ???? What is that?
        Next
        col_count_1_col = prop_1_col.Count ' col_count_1_col = 2 <-- WRONG

- I want to know how to tell that the linq result is 1 column

- I want to get the column name in case of 1 column in the Linq result.

Thanks

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Answer 1

Hi Samir,

Welcome to the MSDN forum.

I guess the type of CustomerID is String. Is that right?

For the first example, the compiler created an anonymous type which have three read-only properties to store each values (t.CustomerID,t.City,t.Address), so you can get three properties. For second, you will get the properties of type of CustomerID. For String type, it only have two properties “Char” and “Length”.

Best Regards,

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Alexander Sun [MSFT]
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Answer 2

Hi  Alexander

+1 for your explanation, but I still find this behavior .... I will use the word "annoying"

Yes, CustomerID is nchar(5) in Northwind SqlServer db and by linq mapping it is NChar(5) NOT NULL

a Linq result should have standards or definition where here I can see it has two, first for 1 column and second for +1 column?

ok, lets solve my problem..

Dim LinqQueryResult = Something

How I can tell if this is 1 column or +1 column and how to extract the column name in case it was 1 column?

Thank you.

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