从SQL中的同一行返回最小值的列名称

Question

I want to retrieve the minimum value and the corresponding column name from table with the same row. See the query for retrieving the minimum value:

SELECT least(supplier1,supplier2,supplier3,supplier4,supplier5) AS minValue 
FROM 
priceTable  
WHERE partno='OL0003';

The above produces 20. Now, i want to pick the 20 and the column name which is Supplier1 in this case. What query do i need to add or is there a refactor code that can help do this at once. I am using mysql

Answer 1

After that, you need a case expression:

SELECT least(supplier1, supplier2, supplier3, supplier4, supplier5) AS minValue,
        (CASE least(supplier1, supplier2, supplier3, supplier4, supplier5)
              WHEN supplier1 THEN 'supplier1'
              WHEN supplier2 THEN 'supplier2'
              WHEN supplier3 THEN 'supplier3'
              WHEN supplier4 THEN 'supplier4'
              WHEN supplier5 THEN 'supplier5'
         END) as column_name_for_min
FROM priceTable  
WHERE partno = 'OL0003';

This would be much simpler if you structured your data better. You should have a table PartSuppliers with one row per part and per supplier.

Then you could get the least value in a variety of ways, such as:

select ps.*
from partsuppliers ps
where ps.cost = (select min(ps2.cost)
                 from partsuppliers ps2
                 where ps2.partno = ps.partno
                );