Question

I have an SQL function:

-- Function: insert_into_wgs()

-- DROP FUNCTION insert_into_wgs();

CREATE OR REPLACE FUNCTION insert_into_wgs()
  RETURNS void AS
$BODY$
BEGIN
INSERT INTO parcels (num,vid,support_num,name_dispatcher,cadastr,the_geom,status_id)  
SELECT num,vid,support_num,name_dispatcher,cadastr,ST_TRANSFORM(the_geom,4326),status_id
FROM parcels_temp
WHERE num NOT IN (SELECT num FROM parcels)AND deleted='no';
end;
$BODY$
LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION insert_into_wgs() OWNER TO postgres;

You see that it works only for parcels, parcels_temp tables. How can I create function with parameters insert_into_wgs(table, table_temp);?

Answer 1

As mentioned in the comment, you have to use dynamic SQL if you want to parametrize identifiers. And use EXECUTE in plpgsql.

In the base query better use NOT EXISTS instead of col NOT IN (<subquery>).

Now, if only the table names change and the columns stay the same, this simple demo would do the job:

CREATE OR REPLACE FUNCTION insert_into_tbl(_tbl text, _tbl_tmp text)
  RETURNS void AS
$func$
BEGIN

EXECUTE format($x$
INSERT INTO %I (...)  -- enter columns
SELECT ...            -- enter columns
FROM %I t
WHERE NOT EXISTS (
    SELECT 1
    FROM   %1$I p     -- reuse first table name
    WHERE  p.num = t.num
    )
AND   deleted = 'no'$x$, _tbl, _tbl_tmp);

END
$func$ LANGUAGE plpgsql;

Check out format() in the manual.
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