using linq to select a column from a datatable

Question

Currently I am using sql and hitting the database to populate a dropdown.

Dim sqlStatement = "SELECT DISTINCT IMLOCN FROM table order by IMLOCN desc"
    LocationDropDown.DataSource = DB.sql(dbSalesWeb, sqlStatement)
    LocationDropDown.DataTextField = "IMLOCN"
    LocationDropDown.DataBind()
    LocationDropDown.Items.Insert(0, "ALL")

DB is a custom class and sql returns a Datatable. I'd like to use linq on a datatable that already has the IMLOCN

 Protected Sub updateDropDowns(ByVal dt As DataTable)


    Dim location = From u In dt.Rows _
                        Select u("IMLOCN") _
                        Distinct

    LocationDropDown.DataSource = location.ToList
    LocationDropDown.DataBind()

End Sub

I've tried dt.AsEnumerable() and Dim location = From u In dt.AsEnumerable _ Select u.Field(Of String)("IMLOCN") _ Distinct I'd like to be able to use linq and I'd like to learn more about it

What's your question? Are you getting an error?

D Stanley
– D Stanley

2013-02-01 00:19:05 +00:00
Commented Feb 1, 2013 at 0:19 — D Stanley
– D Stanley, Commented Feb 1, 2013 at 0:19

dan radu · Accepted Answer · 2013-02-01 01:24:25Z

3

Not sure what error you get, but this query should work fine:

Dim qLocation = (From u In dt.AsEnumerable() _
                Select u.Field(Of String)("IMLOCN")).Distinct()
LocationDropDown.DataSource = qLocation.ToList()
LocationDropDown.DataBind()

answered Feb 1, 2013 at 1:24

dan radu

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3 Comments

Kevin Over a year ago

with the above linq query I get the error " unable to cast object of type System.Byte to type System.string" In the DB IMLOCN is a tiny int. when I look in the debugger Location doesn't have any results in it. If I switch the column to IMSTK which is a varchar in the DB Location actually has results in it, but I get the error "dataBinding System.String does not contain a property with the name IMLOCN" but I switched and used IMSTK instead of IMLOCN, why does the debugger say IMLOCN still?

Kevin Over a year ago

I databind the dropdown when the page is first loaded to the results from a sql query. Is that causing problems with databinding it to the linq results?

Kevin Over a year ago

When I databind to the sql results earlier I am also setting the datatextfield = "IMLOCN" is that causing the string does not contain a property with the name IMLOCN error?

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