Insert record dynamically inside of Procedural Trigger

问题

We are looking to convert our database over to Postgres (9.3.5), which I have no experience with, and I am trying to get our audit tables up and running. I understand that each table will need its own trigger, but all triggers can call a single function.

The trigger on the table is passing a list of the columns that need to be audited since some of our columns are not tracked.

Here are some of the posts I followed:
- https://stackoverflow.com/a/7915100/229897
- http://www.postgresql.org/docs/9.3/static/plpgsql-statements.html
- http://www.postgresql.org/docs/9.4/static/plpgsql-trigger.html

When I run this I get the error: ERROR: syntax error at or near "$1"

DROP TABLE IF EXISTS people;
DROP TABLE IF EXISTS a_people;

CREATE TABLE IF NOT EXISTS people (
  record_id  SERIAL PRIMARY KEY NOT NULL,
  first_name VARCHAR NOT NULL,
  last_name VARCHAR NOT NULL,
  last_updated_on TIMESTAMP NOT NULL DEFAULT  CURRENT_TIMESTAMP 
);

CREATE TABLE IF NOT EXISTS a_people (
  record_id  SERIAL PRIMARY KEY NOT NULL,
  a_record_id INT,
  first_name VARCHAR NULL,
  last_name VARCHAR NULL,
  last_updated_on TIMESTAMP
);
/******************************************************/
--the function
CREATE OR REPLACE FUNCTION audit_func()
RETURNS TRIGGER AS 
$BODY$  
    DECLARE 
        audit   TEXT := TG_TABLE_SCHEMA || '.a_' || TG_TABLE_NAME;
        cols    TEXT := TG_ARGV[0];
    BEGIN
        EXECUTE format('INSERT INTO %1$s(a_%2$s) SELECT %2$s FROM ($1)',  audit, cols) USING OLD;   
        NEW.last_updated_on = CURRENT_TIMESTAMP;
        RETURN NEW;
    END;
$BODY$
LANGUAGE plpgsql;
/******************************************************/
--the trigger calling the function to update inbound records
CREATE TRIGGER build_user_full_name_trg 
BEFORE UPDATE
ON people 
FOR EACH ROW WHEN (OLD.* IS DISTINCT FROM NEW.*)
EXECUTE PROCEDURE audit_func('record_id,first_name,last_name');
/******************************************************/
INSERT INTO people (first_name, last_name) VALUES ('George','Lincoln');
UPDATE people SET last_name = 'Washington' WHERE first_name = 'George';
SELECT * FROM people;

I welcome your assistance (and patience)!

回答1:

This subselect should work:

EXECUTE format('INSERT INTO %1$s(a_%2$s) SELECT %2$s FROM (select ($1).*) XX',  audit, cols) USING OLD;

来源：https://stackoverflow.com/questions/28242672/insert-record-dynamically-inside-of-procedural-trigger

标签

postgresql

postgresql-9.3