Getting null values in an update statement - Mailing list pgsql-novice

From JORGE MALDONADO
Subject Getting null values in an update statement
Date
Msg-id BANLkTikGPsOAmuiXNEn14ogDBvdfND2C4A@mail.gmail.com
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Responses Re: Getting null values in an update statement
List pgsql-novice
I want to perform an UPDATE to a field in a table. Such a field is of type numeric, does not allow null values and has a default value of 0 (zero). The situation I am facing is that the records that do not meet the update criteria are set to null and I do not know why. I get an error message saying that a violation has been made because the field cannot be set to null. Then, I change the field definition so it accepts null values, run the update statement and I confirm that such a field is set to null for the records that do not meed the criteria. How can I avoid this sitution?
Does this behavior has to do with the way I am using the update statement?
Below is the UPDATE statement for your reference.
I appreciate your help in advance.
 
Regards,
Jorge Maldonado
 
UPDATE temp_lista_titulos SET tmt_porc =
  (SELECT SUM(tmt_clave) AS suma FROM
    (SELECT t1.tmt_clave, t1.tmt_album AS album
    FROM temp_lista_titulos as t1, temp_lista_titulos as t2
    WHERE t1.tmt_album = t2.tmt_album AND t1.tmt_clave != t2.tmt_clave) temp
WHERE tmt_album = album
GROUP BY tmt_album)

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