10

I have the following table:

Bank:
name  val   amount
John   1     2000
Peter  1     1999
Peter  2     1854
John   2     1888

I am trying to write an SQL query to give the following result:

name  amountVal1 amountVal2  
John    2000        1888   
Peter   1999        1854

So far I have this:

SELECT name,
CASE WHEN val = 1 THEN amount ELSE 0 END AS amountVal1,
CASE WHEN val = 2 THEN amount ELSE 0 END AS amountVal2
FROM bank

However, it gives the slightly wrong result:

name  amountVal1 amountVal2  
John    2000        0
Peter   1999        0
John    0          1888   
Peter   0          1854

How can I modify my query to give the correct presentation? Thanks

OMG Ponies
  • 325,700
  • 82
  • 523
  • 502
Roger
  • 3,411
  • 5
  • 23
  • 22

2 Answers2

30
SELECT 
  name,
  SUM(CASE WHEN val = 1 THEN amount ELSE 0 END) AS amountVal1,
  SUM(CASE WHEN val = 2 THEN amount ELSE 0 END) AS amountVal2
FROM bank GROUP BY name
nos
  • 223,662
  • 58
  • 417
  • 506
  • That did the trick. I tried using Group by without the SUM and it didn't work. I see now that you could have the same name, with many different values under the columns amountVal1/2. Therefore I assume the `group by name` wouldn't know what to do with the numbers. In this case, we need to tell it to SUM them! Thanks for the help – Roger May 01 '11 at 02:39
3

Looks like you need to join the table on itself. Try this:

select bank1.name, bank1.amount, bank2.amount
from bank bank1
inner join bank bank2 on 
    bank1.name = bank2.name 
    and bank1.val = 1 
    and bank2.val = 2
Brian Willis
  • 22,768
  • 9
  • 46
  • 50
  • Thanks I think this would work also, but I don't want to create a temporary table if possible. – Roger May 01 '11 at 02:41
  • 2
    @Roger: This will not create any temporary table. In some cases, it may even be faster than the `GROUP BY - CASE` approach. – ypercubeᵀᴹ Jul 13 '11 at 09:45
  • But this will show different results if there are persons with rows only for `val=1` or `val=2`. Or with more than one row with same value. – ypercubeᵀᴹ Jul 13 '11 at 09:47