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От | Ken Winter |
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Тема | |
Дата | |
Msg-id | 004e01c5f0ae$c4d4bfe0$6503a8c0@kenxp обсуждение исходный текст |
Ответы |
Re:
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Список | pgsql-sql |
In PL/pgSQL, is there a way to put a *variable* column-name in a dot notation reference to a RECORD column? For example, suppose I want to write a function like the following, which is to be called by a "BEFORE INSERT" trigger: CREATE OR REPLACE FUNCTION foo ( ) RETURNS TRIGGER AS ' DECLARE var VARCHAR; BEGIN var := TG_ARGV[0] NEW.<the column whose name is the value of var> := ''whatever''; RETURN NEW; END; ' LANGUAGE 'plpgsql' ; The aim of this uninteresting function is to assign the value 'whatever' to the table column that is passed in by the calling trigger as TG_ARGV[0], i.e. the first calling argument. What I don't know is what to put into the dot notation in place of ".<the column whose name is the value of var>" so that the column of NEW that is addressed by the assignment statement is the one passed in as the first argument. Is there any PL/pgSQL construct that could be substituted in here to achieve this result? If not, can anybody suggest a way to write a trigger-called function that would accomplish the same result? In case it's not obvious, the underlying goal is to write a single trigger-called function that could modify different columns for each trigger that called it, where each trigger specified the target column by a calling argument (or by any other viable mechanism). ~ TIA ~ Ken
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