Construct a new database schema for the presentation table that better handles timestamps

[SRomansky]

The current database schema:

PRESENTATIONS_SCHEMA_310 = '''CREATE TABLE IF NOT EXISTS presentations                                                                                                                           
                                       (Id INTEGER PRIMARY KEY,                                                                                                                                  
                                        Title varchar(255),                                                                                                                                      
                                        Speaker varchar(100),                                                                                                                                    
                                        Description text,                                                                                                                                        
                                        Category varchar(25),                                                                                                                                    
                                        Event varchar(100),                                                                                                                                      
                                        Room varchar(25),                                                                                                                                        
                                        Date timestamp,                                                                                                                                          
                                        StartTime timestamp,                                                                                                                                     
                                        EndTime timestamp,                                                                                                                                       
                                        UNIQUE (Speaker, Title) ON CONFLICT IGNORE)'''

Does not describe the Date, StartTime, or Endtime that Freeseer expects. It would be useful to have a well defined meaning for what each field is supposed to contain.

Some of the current code in Freeseer expects dates of the format 2010-05-14T10:45 and has resulted in the following code being added:

    if not presentation.date and presentation.startTime and len(presentation.startTime) == 16:
            presentation.date, presentation.startTime = presentation.startTime[:-6], presentation.startTime[11:]

Such code would need to be refactored when a new schema was implemented. The above code also uses the same timestamp format for the presentation.date and presentation.startTime fields.

Related #634, #619, #484

[SRomansky]

#619 (comment) provides an example of how the ambiguous schema creates a bit of confusion.

[zxiiro]

This is handled by QDateTime / QDate / QTime I can't recall which or if all combinations of those are used but as long as your date format is accepted by those Qt will handle the rest. You can probably look up the Qt Docs on those classes to find out what their requirements are.

[SRomansky]

@zxiiro OK. I can dig into that, (I think after #619 and #651 are wrapped up).

[SRomansky]

http://www.pythoncentral.io/advanced-sqlite-usage-in-python/ mentions that if we have a timestamp column then we should have a datetime object. I think this person http://www.qtforum.org/article/34211/qsqlquery-sqlite3-timestamp.html shows using the qdatetime object with a timestamp SQLITE column too.