LINQ如何處理空值

Question

對不起英文不好;

我的代碼;

Dim otherDT As DataTable = retDS1.Tables(0)   
Dim dt As New DataTable 

dt.Columns.Add("COGRAFI_BOLGE_ADI") 
dt.Columns.Add("Count") 

Dim query = (From dr In (From d In otherDT.AsEnumerable Select New With {.COGRAFI_BOLGE_ADI = d("COGRAFI_BOLGE_ADI")}) Select dr.COGRAFI_BOLGE_ADI Distinct) 

For Each colName As String In query 
    Dim cName = colName 
    Dim cCount = (From row In otherDT.Rows Select row Where row("COGRAFI_BOLGE_ADI").ToString = cName).Count 
    dt.Rows.Add(colName, cCount) 
Next 

GridView1.DataSource = dt 
GridView1.DataBind() 

某些行包含空值; 如何處理空行？

輸出：

Marmara 40 
Ege  10 
Akdeniz 2 
... 

Answer 1

真不明白你問什麼，但你在找這樣的事情：

Dim otherDT As DataTable = retDS1.Tables(0)   
Dim dt As New DataTable 
dt.Columns.Add("COGRAFI_BOLGE_ADI") 
dt.Columns.Add("Count") 

Dim query = (From dr In (From d In otherDT.AsEnumerable 
         Select New With {.COGRAFI_BOLGE_ADI = d("COGRAFI_BOLGE_ADI")})   
      Select dr.COGRAFI_BOLGE_ADI Distinct) 

For Each colName As String In query 
    Dim cName As String = colName 
    Dim cCount As Integer = (From row In otherDT.Rows 
          Select row 
          Where row IsNot Nothing AndAlso 
           row("COGRAFI_BOLGE_ADI") IsNot Nothing AndAlso 
           row("COGRAFI_BOLGE_ADI").ToString = cName).Count 
    If cCount > 0 Then 
     dt.Rows.Add(colName, cCount) 
    End If 
Next 

GridView1.DataSource = dt 
GridView1.DataBind()