0 is different to null/NULL. 0 indcates there was a measurement and the value is zero (eg your thermomenter reports 0C). Null indicates there was no measurement or no data (eg you don't have a thermometer). The nulls only matter if they are in a field in which you should (given the capabilities of your station) have observational data. Have a look at the schema used by a default weeWX install (The Archive types appendix <http://weewx.com/docs/customizing.htm#archive_types> to the Customization Guide gives a good indicator, or have a look in bin/schemas/wview.py for the definitive schema). I guarantee there are a lot of fields there that your station woon't be fillling.
Gary On Tuesday, 13 March 2018 20:13:54 UTC+10, Greg from Oz wrote: > > If NULLS are bad why is the default NULL? > I ran this command: > MariaDB [weewx]> SHOW COLUMNS FROM archive FROM weewx; > +----------------------+---------+------+-----+---------+-------+ > | Field | Type | Null | Key | Default | Extra | > +----------------------+---------+------+-----+---------+-------+ > | dateTime | int(11) | NO | PRI | NULL | | > | usUnits | int(11) | NO | | NULL | | > | interval | int(11) | NO | | NULL | | > | barometer | double | YES | | NULL | | > | pressure | double | YES | | NULL | | > | altimeter | double | YES | | NULL | | > | inTemp | double | YES | | NULL | | > | outTemp | double | YES | | NULL | | > | inHumidity | double | YES | | NULL | | > | outHumidity | double | YES | | NULL | | > | windSpeed | double | YES | | NULL | | > | windDir | double | YES | | NULL | | > | windGust | double | YES | | NULL | | > | windGustDir | double | YES | | NULL | | > | rainRate | double | YES | | NULL | | > | rain | double | YES | | NULL | | > | dewpoint | double | YES | | NULL | | > | windchill | double | YES | | NULL | | > | heatindex | double | YES | | NULL | | > | ET | double | YES | | NULL | | > | radiation | double | YES | | NULL | | > > > On Tuesday, 13 March 2018 20:21:16 UTC+11, gjr80 wrote: >> >> Greg, >> >> The --check-strings (and its friend --fix-strings) action is there for >> SQLite databases (do a wee_database --help). It will run on a MySQL >> install but essentially has no effect. Having a null/NULL value in a >> database is fine, that is how the python None values are stored. However, >> having a string or a null string in a weeWX database field is not OK, that >> is what --check-strings will pickup and --fix-strings will fix. I'm not >> sure why the null string only comes up for SQLite databases, before my >> time, though one way that you can easily get them if you are not carfeul is >> through use of a graphical db browser/editor. >> >> Gary >> >> On Tuesday, 13 March 2018 19:02:58 UTC+10, Greg from Oz wrote: >>> >>> Hi, >>> I am using mqysql as my weewx database. >>> I run the wee_database --check-strings and it comes back clean but if I >>> run mysql command to look for NULL I get a lot of results. >>> Anyone know why this would be the case? >>> >>> Thanks >>> >>> wee_database --check-strings >>> Using configuration file /etc/weewx/weewx.conf >>> Using database binding 'wx_binding', which is bound to database >>> 'archive_mysql' >>> Preparing Null String Check, this may take awhile... >>> Checking record: 488186; Timestamp: 2018-03-12 10:05:00 AEDT (1520809500) >>> No null strings found. >>> Completed Null String Check in 28.89 seconds. >>> >>> >>> Yet, if I run the command below it shows I do have NULL values. >>> >>> >>> MariaDB [weewx]> select dateTime, rain , rainRate from archive where >>> rain IS NULL; >>> +------------+------+----------+ >>> | dateTime | rain | rainRate | >>> +------------+------+----------+ >>> | 1501541984 | NULL | 0 | >>> | 1501546184 | NULL | 0 | >>> | 1501563583 | NULL | 0 | >>> | 1501564184 | NULL | 0 | >>> | 1501564490 | NULL | 0 | >>> | 1501585184 | NULL | 0 | >>> | 1501590884 | NULL | 0 | >>> | 1501634684 | NULL | 0 | >>> | 1501635284 | NULL | 0 | >>> | 1501636784 | NULL | 0 | >>> | 1501656884 | NULL | 0 | >>> | 1501659584 | NULL | 0 | >>> | 1501675645 | NULL | 0 | >>> >>> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
