NULL values in query results

Hi support Team, what could be the reason that most values in the query results of my base view appers NULL ?? The base view is successfully created from a SQL SERVER but Iwhen executing I am getting NULL values (for different datatypes : text, int … ) as results. Thank for help regards iris
user
21-09-2019 18:57:01 -0400

6 Answers

Hi, The base view is the exact replica of the table defined in the underlying data source. The Virtual DataPort server just delegates the query to the underlying data source. I suggest you to execute the query and check the [execution trace](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/creating_derived_views/querying_views/execution_trace_of_a_statement) for the same. In addition to this, you can also verify if the underlying data source contains the records for the corresponding columns by executing the same query in the data source itself. Hope this helps!
Denodo Team
23-09-2019 08:16:20 -0400
Thanks for response. Of course the table in the underlying data source is filled with values, while the base view in Denodo gives NULL results. Maybe some other idea...?
user
23-09-2019 09:43:32 -0400
What client tool are you using the query the Denodo server ? If you're using Denodo's VDP Tool and getting a lot of null values like phamtom rows, make sure the Denodo Server and Denodo VDP Tool are on the SAME update level, ie, same version. This happened to me when the VDP Tool had an OLDER version than the update level that was applied to the Denodo server. if you're using other client tool, not sure what's happening, but either way check the JDBC or ODBC drivers you're using are the same version level as the Denodo server.
Denodo Team
23-09-2019 14:14:52 -0400
Hello, I am experiencing a similar issue. When I do a very simple query of my cached base view it works and returns the data, but when I try to add logic like a where clause then it returns null. Just wanted to reach out in case we might be having a similar problem. I posted details on the issue I have here: https://community.denodo.com/answers/question/details?questionId=9060g000000Xf8vAAC&title=Denodo+Cached+View+Issue+%28returns+0+records%29
user
23-09-2019 14:32:50 -0400
Hi and thank you for the quick reply. For now, I am using Denodo Express. The server and tool versions (VDP Tool) are the same: 7.0. Regarding JDBS drivers: I assume that when installing Denodo express the driver versions are the same version level ... ?
user
26-09-2019 03:03:53 -0400
Hi, If you have created the Base view by using [create from query](https://community.denodo.com/kb/view/document/Using%20the%20Create%20Base%20View%20From%20Query%20Option?category=Data+Sources) option, then I suggest you to execute the **query** used for creating the Base view in the underlying Data Source itself. For a better understanding of this issue, I suggest you to check the [execution trace](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/creating_derived_views/querying_views/execution_trace_of_a_statement) of the query. Hope this helps!
Denodo Team
09-10-2019 07:00:28 -0400
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