Mysql：查询字段的最小值和最大值之间的缺失行

Question

I am working with a parts / motorcycle fitment Mysql database where all parts are linked to all motorcycles they can be installed on. It looks like this:

part_number motorcycle      year
1000        HONDA_CBR1000   2008
1000        HONDA_CBR1000   2009
1000        HONDA_CBR1000   2010
1000        HONDA_CBR1000   2011
1000        HONDA_CBR1000   2012
1000        HONDA_CBR1000   2013
1001        HONDA_CBR600    2008
1001        HONDA_CBR600    2009
1001        HONDA_CBR1000   2008
1001        HONDA_CBR1000   2009
1001        HONDA_CBR1000   2013

So it means that:

• part #1000 can be installed on the Honda CBR1000 from 2008 to 2013
• part #1001 can be installed on the Honda CBR600 from 2008 to 2009 AND on the Honda CBR1000 from 2008 to 2013.

Unfortunately, the table (which has ~650,000 rows) was not always filled correctly. In this example, you will notice the following lines are missing:

part_number motorcycle      year
1001        HONDA_CBR1000   2010
1001        HONDA_CBR1000   2011
1001        HONDA_CBR1000   2012

because the part #1001 which can be installed on the HONDA_CBR1000 from 2008, 2009 and 2013 can also be installed in the "forgotten" years in between (2010, 2011 and 2012).

So the simple query:

SELECT * FROM mytable WHERE motorcycle = 'HONDA_CBR1000' AND year = '2011'

would only retrieve the row for part #1000 (while in reality, part #1001 is also installable on this bike).

in plain English, I guess a query like

SELECT * FROM mytable WHERE motorcycle = 'HONDA_CBR1000'
AND ("minimum year of part_number applicable to HONDA_CBR1000" <= '2011')
AND ("maximum year of part_number applicable to HONDA_CBR1000" >= '2011')

would retrieve all results (1000 and 1001).

But how can I ask that in SQL? Do you think it would too slow?

Thanks for any help!

Answer 1

SELECT part_number, max(year), Min(year) 
  FROM mytable 
WHERE motorcycle = 'HONDA_CBR1000'
Group By part_number
Having Min(year) <= 2011
  And max(year) >= 2011

*********************Edit****************

To improve performance, Lets try this, 1)

 SELECT part_number 
          FROM mytable t, 
               (Select part_number, Min(year) Minyear, max(year) Maxyear
                  FROM mytable
                Group BY part_number) t1
        WHERE t.motorcycle = 'HONDA_CBR1000'
           AND t.year Between MinYear and Maxyear
           AND t.year = '2011'

*********************EDIT 2**********************************

So This is the query that will list out the years that are missed out. You can put the entire query in to a insert statement

SELECT partsnumber ,  yrs.allyears
  FROM (Select max(year) maxyear, min(year) minyear, partsnumber
          FROM yourtable
      group by partsnumber) q1   
        (Select 1950+1+b+a*10 as allyears
           from (select 0 as a union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) a,
                 (select 0 as b union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) b) y
    Where yrs.allyears between maxyear and minyear

MINUS
SELECT partsnumber ,  yrs.allyears
 From yourtable

yrs --> Subquery that generates years from 1950 to 2050 (If you have more years ( beyond 2050 or before 1950 ) then this has to be changed)

Am selecting the years between the min and max years for each productnumber. then with yrs table as reference am finding the years between min and max years.

The result from above query will give all years between min and max. The minus will give the years that are missed

Answer 2

Here is my approach for getting all combinations of parts and motorcycles and the years they have no data.

Generate all the rows for all the years, then filter out the ones you have. The first part uses cross join . The second left join :

select pm.part_number, pm.motorcycle, y.year
from (select part_number, motorcycle, min(year) as miny, max(year) as maxy
      from mytable
      group by part_number, motorcycle
     ) pm cross join
     (select distinct year
      from mytable
     ) y
     on y.year between pm.miny and pm.maxy left join
     mytable t
     on t.part_number = pm.part_number and t.motorcycle = pm.motorcycle and
        t.year = y.year
where y.year is null;

This assumes that all years are in your table, somewhere. The y table is just a list of years, so you can get it from another table or by creating a derived table. The subquery is just a convenient way to get it.