Question

Here is description of my scenario:

myTable:

ID name width1 width2 parameter1 parameter2 code
1  AAA  0      10     500        750        10001
2  AAA  0      10     750        1250       10002 
3  AAA  0      10     900        1400       10003
4  AAA  0      10     1150       1650       10004
.................................................
.................................................
.................................................

Lets say that I’m working with some “subjects” that have their own properties. Based on subject properties and some calculations with that same properties I should take “code” from this table.

So, this one subject that I’m currently working with has name: AAA, width: 5, and with my calculations i get parameter: 1000. After I have all of necessary attributes I can compare them with rows in myTable. For bigger picture I’ll select all from this table but my goal is to get code. Here is query for that:

SELECT * FROM myTable WHERE name="AAA" AND 5>=width1 AND 5<=width2 AND 1000>=parameter1 AND 1000<=parameter2

After this I get these two rows:

ID name width1 width2 parameter1 parameter2 code
2  AAA  0      10     750        1250       10002 
3  AAA  0      10     900        1400       10003

Just to mention, here could be one row. But, if I get two rows I need to do following. My whole concentration is on these parameters in a way that I’m comparing spread between my parameter and parameter2 in first row and spread between my parameter and parameter1 in second row.

parameter -> parameter2
1250 - 1000 = 250
&
parameter1 -> parameter
1000 - 900 = 100

So, if spread1:250 > spread2:100 take code2:00002 else take code3:00003.

My question is, how to compare values from different rows and columns? As you can see I have two rows and values from different column. What I need is a way to select these specific values for comparison.

Thank you.

Answer 1

It seems to be solved by Greatest from Least, so at first we get the least value and order this descent.

SELECT 
  code
FROM 
  myTable 
WHERE 
  name="AAA" 
AND 
  5 >= width1 
AND 
  5 <= width2 
AND 
  1000 >= parameter1 
AND 
  1000 <= parameter2
ORDER BY 
  Least( parameter2-1000, 1000-parameter1 ) desc
LIMIT 1;

SQL Fiddle