主题：跨表引用慢

老师，跨表引用慢，怎么解决呢？

Dim cmd As New SQLCommand
Dim dt As DataTable
cmd.C
cmd.CommandText = "S  ELECT DISTINCT 合同编码,所属机构,项目名称,合同金额 From {合同签订}"
dt = cmd.ExecuteReader()
If  e.DataCol.Name = "项目名称" Then
     Dim nms()As String = {"合同编码","所属机构","合同金额"}
     If  e.NewValue Is Nothing Then 
         For Each nm As String In nms
             e.DataRow(nm)= Nothing 
         Next 
     Else 
         Dim dr As DataRow
         dr = dt.Find("[项目名称]= '" & e.NewValue & "'") 
         If  dr IsNot Nothing
             For Each nm As String In nms
                 e.DataRow(nm)= dr(nm)
             Next
         End If
     End If
End If