QGIS 2.0, SpatiaLite: labels disappear after setting data defined position (x,y)

Question

I added to my SpatiaLite table (.osm-import with the "standard" QGIS-OSM-Plugin) two empty columns x and y (double) to define manually the position of my labels (data defined labeling). But after telling the layer about the x and y-column, all labels just disapears!

I tested it in different CRS and with different data types and lengths. I created the columns in QGIS (When I create them in DB-Manager or Qspatialite, they wont appear in the QGIS attribute table)

Im absolutely new to SQL databases!

Thats my table:

UPDATE:

Creating a column with

ALTER TABLE "pelepo_300114_place" ADD COLUMN label_x integer

works but is NOT displayed in Qgis. (I tryed it with integer, numeric, float...)

Answer 1

You say you are defining two empty columns X and Y of type double, but on the screenshots they appear as integers. Also, there is no double type as numeric on sqlite:

• http://www.sqlite.org/datatypes.html
• http://www.sqlite.org/datatype3.html

Which version os spatialite are you using?

Can you add the columns with an sql command with the shell?

Answer 2

This is certainly related to this bug: http://hub.qgis.org/issues/9148

Basically, in database tables, you can't use a null value for default coordinates when using doubles (or equivalent). Look into the issue tracker to find out why.

My workaround is to use string for those X and Y label coordinates. QGIS handles null/empty strings as you expect, meaning that default values don't need to be manually entered.