From: | Andreas Fromm <Andreas(dot)Fromm(at)physik(dot)uni-erlangen(dot)de> |
---|---|
To: | List pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: add constraints to views |
Date: | 2003-09-20 14:02:28 |
Message-ID: | 3F6C5DF4.10006@physik.uni-erlangen.de |
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Lists: | pgsql-general |
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Gaetano Mendola wrote:
| Andreas Fromm wrote:
|
|> CREATE VIEW test_view (
|> ~ SELECT * FROM test_table WHERE tag
|> );
|>
|> Now I want ad a NOT NULL constraint to the view on field1. I tryed the
|> following, but neither works.
|
|
| what does mean add a null constrain to a view ? Do you mean
| filter out the records with the field1 null ?
|
| CREATE OR REPLACE test_view AS
| SELECT *
| FROM test_table
| WHERE field1 IS NOT NULL AND
| tag;
|
No, I mean that the view behaves like a table with the same columns as
table, but that restricts to records on wich tag is set. To insert a
record to this "special" table it requires to have field1 set. In other
words: A record of table is a record of view if tag is set. If tag is
set, then field1 has also have to have a value. If tag is not set, it
may have a value for field1, but will not show up in the view. Of course
I could achive this be triggers, but I thought it could be possible to
do via constraints on the view.
Regards
Andreas
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