Question

I am working on a project where I need to get the minimum and maximum date from a database as well substringing the first part of a field up to a character and grouping by this field. So basically in the database I have

2012-01-01 Unknown username/password attempted to login. User: admin

2012-01-01 Failed to add user account. MySQL Error: certain my sql
error Unknown

2012-01-02 Failed to add user account. MySQL Error: certain my sql
error Unknown

2012-01-04 Unknown username/password attempted to login. User:
administrator

Below is the query that I am using which is working without showing the date

SELECT ala_type, partMsg, 
wholeMsg, ala_level, ala_page, COUNT(wholeMsg) AS msgCount FROM
(
SELECT ala_type, SUBSTRING_INDEX(ala_message, ':', 1) AS partMsg, ala_message AS wholeMsg,
ala_level, ala_page FROM alarms a) p
GROUP BY partMsg

This bit is grouping correctly as expected but if I try to add a min(date_field) it then only shows one record.

Below is the query that I have tried

SELECT ala_date, min(ala_date), max(ala_date), ala_type, partMsg,
wholeMsg, ala_level, ala_page, COUNT(wholeMsg) AS msgCount FROM (
SELECT ala_date, min(ala_date), max(ala_date), ala_type,
SUBSTRING_INDEX(ala_message, ‘:’, 1) AS partMsg, ala_message AS
wholeMsg, ala_level, ala_page FROM alarms a) p GROUP BY partMsg

If I don’t put ala_date in the second statement and just have min(ala_date) it says that it can’t find the field ala_date. However, when I run the query I am only getting one record and I would have expected to see the following

2012-01-01 2012-01-04 Unknown username/password attempted to login.User: 2

2012-01-01 2012-01-02 Failed to add user account. MySQL Error: > certain mysql error 2

The 2 and the end of the expected result is the count how many times the message occurred.

What I am actually getting is:

2012-01-01 2012-01-01 2012-01-01 Failed to add user account… 1

It is now only showing 1 record and the min and max only are the same and the count is 1 instead of 2.

What could I do to get what I am expecting to get.

Thanks for any help you can provide.

Answer 1

You would do something like (my mysql is rusty) but the theoiry is sound.

Select SomeDate,SomeMessage From SomeTable
inner join (
Select Min(SomeDate) as SomeDate From SomeTable) earliest
On earliestDate.SomeDate = SomeTable.SomeDate

ie find the minimum date for for each group then join back to the original table to find the records that were also on that date.