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Delete min Firebird SQL Development forum discussing administration, Firebird SQL syntax, or other Firebird SQL-related topics. Firebird is the evolution of Borland's Interbase product.

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  #1  
Old March 19th, 2008, 05:36 AM
jennyferlai jennyferlai is offline
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Delete min
Hi! I have a patient's table with 3 fields:
NUMPAT is the number of the patient
TREATMENT is a treatment code
DATE a date
There are many dates for each patient and I need to select the minimun date for each patient. This SQL works fine:

SELECT T.NUMPAT,T.TREATMEN T,T.DATE
FROM MYTABLE T
WHERE
T.DATE=
(SELECT MIN(Q.DATE) FROM
MYTABLE Q WHERE T.NUMPAT = Q.NUMPAT )
order by T.NUMPAT

By now I need to delete that minimun date for each patient, and simply change the first SELECT for a DELETE is not working... how could I?
Sorry for this so simple question...
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  #2  
Old March 19th, 2008, 05:55 AM
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pabloj pabloj is offline
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Why something like this shouldn't work? What error message do you get?
sql Code:
Original - sql Code 
  1. DELETE 
  2. FROM 
  3.  pat_hist p 
  4. WHERE 
  5.  p.pat_date = 
  6. (
  7.   SELECT 
  8.    MIN(a.pat_date) 
  9.   FROM 
  10.    pat_hist a 
  11.   WHERE 
  12.    a.pat_Name = p.pat_name
  13. )
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  #3  
Old March 19th, 2008, 06:01 AM
shammat shammat is offline
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Code:
DELETE FROM 
FROM MYTABLE 
WHERE "DATE" = (SELECT MIN(Q.DATE) 
FROM MYTABLE Q WHERE MYTABLE.NUMPAT = Q.NUMPAT)
should work.
But I strongly recommend not to use a reserved word (DATE) as a column name!
Comments on this post
pabloj agrees!
Annie79 agrees!
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  #4  
Old March 19th, 2008, 07:10 AM
jennyferlai jennyferlai is offline
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Yes, something like this should work, but does not, I don't know why, it deletes the whole table

DELETE
FROM
MYTABLE p
WHERE
p.DATA =
(
SELECT
MIN(a.DATA)
FROM
MYTABLE a
WHERE
a.C_HISTORIA = p.C_HISTORIA
)
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