如何从lambda查询中删除DBnull值？

Question

i have this query

        DataSetTest DB = new DataSetTest();
        DataSetTestTableAdapters.TESTTableAdapter ADPT = new DataSetTestTableAdapters.TESTTableAdapter();
        ADPT.Fill(DB.TEST);

         try
        {
            var xx = DB.TEST.Where(s => s.Name != null).Select(s => s.Name).ToList();
        }
        catch (Exception ex)
        {
            var x = ex;
        }

But it give me this error

{"The value for column 'Name' in table 'TEST' is DBNull."}

so how can i allow DBnull value in the list or remove it many thanks in advance fro any help

Answer 1

var xx = DB.TEST.Where(s => !string.IsNullOrEmpty(Convert.ToString(s.Name))).Select(s => s.Name).ToList();

Answer 2

Try this:

var xx = DB.TEST.Where(s => !string.IsNullOrEmpty(s.Name.ToString())).Select(s => s.Name).ToList();

When s.Name is DBNull then ToString() will return string.Empty

Answer 3

谢谢大家，我只用IsNameNull()方法就可以了

var xx = DB.TEST.Where(s => !s.IsNameNull()).Select(s => s.Name).ToList();