The error "field column T1 could not identified" occurs when the column name does not exist in the view. When I executed the similar query, I specified the column name as it is in the view and it worked for me perfectly with Left join, Inner join, Right join.
Besides that, in Virtual DataPort ensure your data source supports Left join by checking the properties in Source configuration (Data source > Edit).
For more information related to Source Configuration refer the section[ Data Source Configuration Properties](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/creating_views/importing_data_sources_and_creating_base_views/data_source_configuration_properties#data-source-configuration-properties) in Virtual DataPort Administration Guide and refer the section [WITH Clause](https://community.denodo.com/docs/html/browse/6.0/vdp/vql/queries_select_statement/with_clause/with_clause#with-clause) in Virtual DataPort VQL Guide for the syntax to implement Common table expression.
Hope this helps.