What's the best way to select the minimum value from several columns?

Question

Given the following table in SQL Server 2005:

ID   Col1   Col2   Col3
--   ----   ----   ----
1       3     34     76  
2      32    976     24
3       7             


        

Answer 1

If the columns were integers as in your example I would create a function:

create function f_min_int(@a as int, @b as int) 
returns int
as
begin
    return case when @a < @b then @a else coalesce(@b,@a) end
end

then when I need to use it I would do :

select col1, col2, col3, dbo.f_min_int(dbo.f_min_int(col1,col2),col3)

if you have 5 colums then the above becomes

select col1, col2, col3, col4, col5,
dbo.f_min_int(dbo.f_min_int(dbo.f_min_int(dbo.f_min_int(col1,col2),col3),col4),col5)

Answer 2

If you know what values you are looking for, usually a status code, the following can be helpful:

select case when 0 in (PAGE1STATUS ,PAGE2STATUS ,PAGE3STATUS,
PAGE4STATUS,PAGE5STATUS ,PAGE6STATUS) then 0 else 1 end
FROM CUSTOMERS_FORMS

Answer 3

On MySQL, use this:

select least(col1, col2, col3) FROM yourtable

Answer 4

SELECT [ID],
            (
                SELECT MIN([value].[MinValue])
                FROM
                (
                    VALUES
                        ([Col1]),
                        ([Col1]),
                        ([Col2]),
                        ([Col3])
                ) AS [value] ([MinValue])
           ) AS [MinValue]
FROM Table;

Answer 5

If you're able to make a stored procedure, it could take an array of values, and you could just call that.

Answer 6

Below I use a temp table to get the minimum of several dates. The first temp table queries several joined tables to get various dates (as well as other values for the query), the second temp table then gets the various columns and the minimum date using as many passes as there are date columns.

This is essentially like the union query, the same number of passes are required, but may be more efficient (based on experience, but would need testing). Efficiency wasn't an issue in this case (8,000 records). One could index etc.

--==================== this gets minimums and global min
if object_id('tempdb..#temp1') is not null
    drop table #temp1
if object_id('tempdb..#temp2') is not null
    drop table #temp2

select r.recordid ,  r.ReferenceNumber, i.InventionTitle, RecordDate, i.ReceivedDate
, min(fi.uploaddate) [Min File Upload], min(fi.CorrespondenceDate) [Min File Correspondence]
into #temp1
from record r 
join Invention i on i.inventionid = r.recordid
left join LnkRecordFile lrf on lrf.recordid = r.recordid
left join fileinformation fi on fi.fileid = lrf.fileid
where r.recorddate > '2015-05-26'
 group by  r.recordid, recorddate, i.ReceivedDate,
 r.ReferenceNumber, i.InventionTitle



select recordid, recorddate [min date]
into #temp2
from #temp1

update #temp2
set [min date] = ReceivedDate 
from #temp1 t1 join #temp2 t2 on t1.recordid = t2.recordid
where t1.ReceivedDate < [min date] and  t1.ReceivedDate > '2001-01-01'

update #temp2 
set [min date] = t1.[Min File Upload]
from #temp1 t1 join #temp2 t2 on t1.recordid = t2.recordid
where t1.[Min File Upload] < [min date] and  t1.[Min File Upload] > '2001-01-01'

update #temp2
set [min date] = t1.[Min File Correspondence]
from #temp1 t1 join #temp2 t2 on t1.recordid = t2.recordid
where t1.[Min File Correspondence] < [min date] and t1.[Min File Correspondence] > '2001-01-01'


select t1.*, t2.[min date] [LOWEST DATE]
from #temp1 t1 join #temp2 t2 on t1.recordid = t2.recordid
order by t1.recordid