Uredi

Deli z drugimi prek

Skip Clause (Visual Basic)

  • Članek

Bypasses a specified number of elements in a collection and then returns the remaining elements.

Syntax

Skip count

Parts

count
Required. A value or an expression that evaluates to the number of elements of the sequence to skip.

Remarks

The Skip clause causes a query to bypass elements at the beginning of a results list and return the remaining elements. The number of elements to skip is identified by the count parameter.

You can use the Skip clause with the Take clause to return a range of data from any segment of a query. To do this, pass the index of the first element of the range to the Skip clause and the size of the range to the Take clause.

When you use the Skip clause in a query, you may also need to ensure that the results are returned in an order that will enable the Skip clause to bypass the intended results. For more information about ordering query results, see Order By Clause.

You can use the SkipWhile clause to specify that only certain elements are ignored, depending on a supplied condition.

Example

The following code example uses the Skip clause together with the Take clause to return data from a query in pages. The GetCustomers function uses the Skip clause to bypass the customers in the list until the supplied starting index value, and uses the Take clause to return a page of customers starting from that index value.

Public Sub PagingSample()
    Dim pageNumber As Integer = 0
    Dim pageSize As Integer = 10

    Dim customersPage = GetCustomers(pageNumber * pageSize, pageSize)

    Do While customersPage IsNot Nothing
        Console.WriteLine(vbCrLf & "Page: " & pageNumber + 1 & vbCrLf)

        For Each cust In customersPage
            Console.WriteLine(cust.CustomerID & ", " & cust.CompanyName)
        Next

        Console.WriteLine(vbCrLf)

        pageNumber += 1
        customersPage = GetCustomers(pageNumber * pageSize, pageSize)
    Loop
End Sub

Public Function GetCustomers(ByVal startIndex As Integer,
                             ByVal pageSize As Integer) As List(Of Customer)

    Dim customers = GetCustomerList()

    Dim returnCustomers = From cust In customers
                          Skip startIndex Take pageSize

    If returnCustomers.Count = 0 Then Return Nothing

    Return returnCustomers
End Function

See also