query: link with duplicated columns leads "OperationalError: Duplicate column name" on MySQL

[Jun Omae]

The query: link with duplicated columns, e.g. query:col=version|version, leads OperationalError: Duplicate column name on MySQL. No errors on SQLite and PostgreSQL.

This issue is similar to TicketQuery macro issue in comment:9:ticket:11140.

2014-09-30 15:53:20,340 Trac[util] DEBUG: SQL: u"SELECT COUNT(*) FROM (SELECT t.id AS id,t.version AS version,t.version AS version,t.status AS status,t.priority AS priority,t.time AS time,t.changetime AS changetime,priority.value AS priority_value\nFROM ticket AS t\n  LEFT OUTER JOIN enum AS priority ON (priority.type='priority' AND priority.name=priority)\nORDER BY COALESCE(priority.value,'')='',CAST(priority.value AS signed),t.id) AS foo"
2014-09-30 15:53:20,340 Trac[util] DEBUG: execute exception: <_mysql_exceptions.OperationalError instance at 0x7f22e48a6e18>
2014-09-30 15:53:20,341 Trac[main] ERROR: Internal Server Error:
Traceback (most recent call last):
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/web/main.py", line 522, in _dispatch_request
    dispatcher.dispatch(req)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/web/main.py", line 243, in dispatch
    resp = chosen_handler.process_request(req)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/ticket/query.py", line 952, in process_request
    return self.display_html(req, query)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/ticket/query.py", line 1052, in display_html
    tickets = query.execute(req, db)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/ticket/query.py", line 301, in execute
    self.num_items = self._count(sql, args, db)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/ticket/query.py", line 282, in _count
    cursor.execute(count_sql, args)
  File "/venv/trac/0.12.5/lib/python2.4/site-packages/trac/db/util.py", line 56, in execute
    r = self.cursor.execute(sql)
  File "/venv/py24/lib/python2.4/site-packages/MySQLdb/cursors.py", line 205, in execute
    self.errorhandler(self, exc, value)
  File "/venv/py24/lib/python2.4/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
    raise errorclass, errorvalue
OperationalError: (1060, "Duplicate column name 'version'")

[Jun Omae]

The issue has been fixed by #11140 and [12298] (0.12.6).