Hi Michaël,

Larry’s DB Query is the most robust SQL client for all databases that it 
support because it is so simple. It just executes the SQL query and builds a 
layer from the result. It does not read and resolve the metadata tables (like 
geometry_columns, spatial_ref_sys). Therefore it does not matter if the 
metadata is wrong or missing. Valid gpkg and spatialite databases should have 
metadata in place but sometimes it is convenient to create temporary tables 
simply with “create table as select something from somewhere”. That DB Query 
deals also with queries which do not return geometry by creating an empty 
geometry on-the-fly. The DB Query plugin supports also Oracle Spatial. That is 
a need that is year by year less important, based on the number of questions in 
the gis.stackexchange and the mailing lists that I follow. But my view is 
probably restricted based on 
https://blogs.oracle.com/database/oracle-databases-top-db-engines-ranking. The 
decrease in popularity seems to be still real 
https://db-engines.com/en/ranking_trend/system/Oracle.

With Geopackage and Spatialite the Run datastore query does almost the same 
than DB Query. The biggest difference is that the result of the query must 
contain geometry. It might not be very difficult to add an empty geometry like 
DB Query does. When is comes to user friendliness, in DB Query the user must 
write the path to the gpkg/sqlite file by hand. Both can read the geopackage 
and spatialite geometries natively, without spatialite binaries. They are 
naturally needed for getting access to the spatialite functions.  DB Query has 
problems with some geometry types, I think it cannot read XYZ geometries. The 
OpenJUMP DB allows to save the connection with Connection Manager. That means a 
few additional clicks if user wants to check some geopackage/spatialite db  
just once, but saves some keyclicks when the same gpkg/sqlite file is used 
again.

The Spatialite plugin is something different. It offers a graphical user 
interface for the data in the spatialite database, but also for the spatialite 
functions. See some images and examples in 
http://ojwiki.soldin.de/index.php?title=OpenJUMP_with_SpatialLite#Using_SpatiaLite_with_Spatialite_Reader_Plugin.
 It has been a pretty nice tool for workshops about spatial SQL for beginners 
because it saves a lot of writing and helps with the syntax of the functions by 
showing the tooltip hints and by writing the template of the SQL by double 
clicking the function. The down side is that it requires the Spatialite 
binaries and it is in a need of quite heavy update for adding all the new 
Spatialite functions into the GUI. Last time when I did that it took about a 
week to add and test. It may even be hard to make the plugin to run at the 
moment. I have saved an old complete zip with OJ, the plugin, the spatialite 
binaries, and java for the workshops.

I would say that the biggest problem with Spatialite reader plugin is that it 
is written for a wrong database. It should offer the menu access to PostGIS 
functions with all the helper features. Oracle would be a nice pair with its 
own spatial functions with peculiar syntax.

The OpenJUMP wizard reads spatial databases as they are supposed to be read: by 
starting from the metadata. Only tables which are registered into 
geometry_columns are available and the use of SQL is limited to filtering with 
“where”. Fortunately the same connections are available automatically for Run 
datastore query if users just know that.

My conclusion is that the Spatialite reader plugins has certainly very few 
users, it is difficult to install, and it would require a face lift. So perhaps 
it may go. DB Query might be good to keep because of Oracle support but for 
gpkg/spatialite it is not necessary. And it would be nice if the native 
OpenJUMP datastore could be made to handle the queries that does not return 
geometry.

-Jukka Rahkonen-



Lähettäjä: Michaud Michael <m.michael.mich...@orange.fr>
Lähetetty: sunnuntai 25. huhtikuuta 2021 20.52
Vastaanottaja: OpenJump develop and use <jump-pilot-devel@lists.sourceforge.net>
Aihe: [JPP-Devel] OpenJUMP and spatialite/geopackage


Hi Jumpers,

I think we have 3 options to read spatialite : OpenJUMP wizard, Larry's dbquery 
and spatialite plugin. I think we should put our work on one of them, but as 
I'm not familiar with spatialite/geopackage, I'd like to know which important 
capabilities dbquery and spatialite have to offer which are not present in 
OpenJUMP core.

Thank you,

Michaël
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