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DB Select - Logic Meltdown!

Posted on 2011-09-17
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Last Modified: 2012-05-12
Hello Experts - I've been struggling with this one for a while.
[sample table]
----------------------
ITEM         GROUP
----------------------
4            A
7            A
3            A
8            A
7            B
6            B
9            B
0            C
4            C
2            C
5            C
4            C
7            C
5            D
9            D
2            E
7            E
1            E
4            E
7            F
3            F
9            F
6            F
8            G
4            H
5            H
3            H
9            H
0            H
8            H



I need an sql query that will tell me how many times each "ITEM", on a range of SELECT DISTINCT ITEM appeared with one another in a particular group.  

IE:
Items 4 and 8 appeared 2 times (groups A and H).
Items 0 and 4 appeared 2 times (groups C and H).
Items 7, 6 and 9 appeared appeared 2 times (groups B and F).

Can it be done?  Thanks
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Question by:rita_corp
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5 Comments
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 36554697
so, you want to find out the "pairs" of values that appear in the same group(s)?
0
 

Author Comment

by:rita_corp
ID: 36554711
yes (pardon) pairs of items (two items or greater) in the same group(s)
0
 
LVL 4

Accepted Solution

by:
Fugas earned 2000 total points
ID: 36555707
Hi, I don't know what you really need, but this could help you
select item, group_concat(DISTINCT `group` order by `group` ASC) from items group by item;
0
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 36556742
let's try:
select i.item item_1, i2.item_2, i.group group_1, i2.group group_2
from yourtable i
join yourtable oi
  on o.group = i.group
 and o.item <> i.item
join yourtable og
  on og.item = i.item
  and og.group <> i.group
join yourtable i2
  on i2.item = oi.item
 and i2.group = og.group 

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0
 

Author Closing Comment

by:rita_corp
ID: 36558187
Wow - what a gem group_concat was.  Definitely have application for this in the future!  I'm trying to see if I can get this functionality over oracle, but this was a fantastic start!
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