Perhaps this can help you...
Private Function GetMaterial()
Dim _DBCurrentAddIn As AstorCurrentAddIn = AstorCurrentAddIn.Instance
Dim _TableMaterialCurrentAddIn As System.Data.DataTable = _DBCurrentAddIn.ReadTable("Material")
Dim _CollectionMaterialCurrentAddIn As IEnumerable(Of String) = _TableMaterialCurrentAddIn.AsEnumerable().Select(Of String)(Function(_Row As DataRow) _Row.Field(Of String)("RunName"))
Dim _DBBase As AstorBase = AstorBase.Instance
Dim _TableMaterialBase As System.Data.DataTable = _DBBase.ReadTable("Material")
Dim _CollectionMaterialBase As IEnumerable(Of String) = _TableMaterialBase.AsEnumerable().Select(Of String)(Function(_Row As DataRow) _Row.Field(Of String)("RunName"))
Dim _CollectionMaterial As IEnumerable(Of String) = _CollectionMaterialBase.Concat(_CollectionMaterialCurrentAddIn)
Return _CollectionMaterial
End Function
