System.Data.Tests.DataTableTest.SelectFunctions C# (CSharp) Method

        public void SelectFunctions()
        {
            DataTable T = new DataTable("test");
            DataColumn C = new DataColumn("name");
            T.Columns.Add(C);
            C = new DataColumn("age");
            C.DataType = typeof(int);
            T.Columns.Add(C);
            C = new DataColumn("id");
            T.Columns.Add(C);
            DataRow Row = null;

            for (int i = 0; i < 1000; i++)
            {
                Row = T.NewRow();
                Row[0] = "human" + i;
                Row[1] = i;
                Row[2] = i;
                T.Rows.Add(Row);
            }

            Row = T.NewRow();
            Row[0] = "human" + "test";
            Row[1] = DBNull.Value;
            Row[2] = DBNull.Value;
            T.Rows.Add(Row);

            Assert.Equal(25, T.Select("age = 5*5")[0]["age"]);
            Assert.Equal(901, T.Select("len(name) > 7").Length);
            Assert.Equal(125, T.Select("age = 5*5*5 AND len(name)>7")[0]["age"]);
            Assert.Equal(1, T.Select("isnull(id, 'test') = 'test'").Length);
            Assert.Equal(1000, T.Select("iif(id = '56', 'test', 'false') = 'false'").Length);
            Assert.Equal(1, T.Select("iif(id = '56', 'test', 'false') = 'test'").Length);
            Assert.Equal(9, T.Select("substring(id, 2, 3) = '23'").Length);
            Assert.Equal("123", T.Select("substring(id, 2, 3) = '23'")[0]["id"]);
            Assert.Equal("423", T.Select("substring(id, 2, 3) = '23'")[3]["id"]);
            Assert.Equal("923", T.Select("substring(id, 2, 3) = '23'")[8]["id"]);
        }