Mark Wilson <[EMAIL PROTECTED]> wrote:
> Two related questions.
> 1. I have a table with a "date" field. (Ex: '04/13/2002'). I want to get a list
> of all UNIQUE values for that field (many entries from the same day), i.e., all
> days with entries.
> **************************************
> CREATE TABLE metrics_events_power {
> mep_id int(11) NOT NULL auto_increment,
> mep_date text,
> mep_time time DEFAULT '00:00:00' NOT NULL
> }
> INSERT INTO metrics_events_power VALUES ('1', '04/13/2002', '10:41:19');
> INSERT INTO metrics_events_power VALUES ('1', '04/13/2002', '10:46:19');
> INSERT INTO metrics_events_power VALUES ('1', '04/14/2002', '11:51:19');
> **************************************
>
> I want a query that returns for this data '04/13/2002' and '04/14/2002'.
Use WHERE clause to set retrieval conditions for rows, f.e WHERE mep_date='04/13/2002'
OR mep_date='04/14/2002', and GROUP BY mep_date.
Why do you use TEXT column type for the dates? You can use DATE column type and
DATE_FORMAT() function:
http://www.mysql.com/doc/en/DATETIME.html
http://www.mysql.com/doc/en/Date_and_time_functions.html
>
> 2. Now I have X tables with those date fields. How do I get a list from all
> specified tables with the unique dates from them? For instance, 2 more tables:
>
> **************************************
> CREATE TABLE arf_events_power {
> aep_id int(11) NOT NULL auto_increment,
> aep_date text,
> aep_time time DEFAULT '00:00:00' NOT NULL
> }
> INSERT INTO arf_events_power VALUES ('1', '05/13/2002', '10:41:19');
> INSERT INTO arf_events_power VALUES ('1', '05/24/2002', '10:46:19');
> INSERT INTO arf_events_power VALUES ('1', '06/21/2002', '11:51:19');
>
> CREATE TABLE blah_events_power {
> bep_id int(11) NOT NULL auto_increment,
> bep_date text,
> bep_time time DEFAULT '00:00:00' NOT NULL
> }
> INSERT INTO blah_events_power VALUES ('1', '04/13/2002', '10:41:19');
> INSERT INTO blah_events_power VALUES ('1', '04/13/2002', '10:46:19');
> INSERT INTO blah_events_power VALUES ('1', '07/28/2002', '11:51:19');
> **************************************
>
> Should return 6 dates:
> '04/13/2002'
> '04/14/2002'
> '05/13/2002'
> '05/24/2002'
> '06/21/2002'
> '07/28/2002'
Use UNION:
http://www.mysql.com/doc/en/UNION.html
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