[migration] More resilient migration script
Query the information schema to retrieve existing constraint (primary key and
unique) and drop them.
Thus don't use anymore DROP CONSTRAINT IF EXISTS (not implemented by e.g. old
versions of sqlserver). To do so a missing DISTINCT was necessary to avoid
duplicates.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*