How to pass the value of NEW using dollar quoting? - sql

Question

I cannot access the value of the NEW row inside my crosstab() query string.
CREATE OR REPLACE FUNCTION insert_fx()
RETURNS TRIGGER AS
$BODY$
BEGIN
INSERT INTO outputtb (serial,date, judge)
VALUES (NEW.serial, NEW.date, NEW.tjudge) RETURNING serial INTO newserial;
UPDATE outputtb
SET (reading1,
reading2,
reading3) =
(SELECT ct."reading1",
ct."reading2",
ct."reading3"
FROM crosstab( $$
SELECT tb2. serial,tb2. readings,tb2. value
FROM DATA AS tb2
INNER JOIN outputtb AS tb1 USING (serial)
WHERE tb2.serial = $$||NEW.serno||$$
ORDER BY 1 ASC $$, $$
VALUES ('reading1'),('reading2'),('reading3')$$
) ct ("Serial" VARCHAR(50),"Reading1" FLOAT8, "Reading2" FLOAT8, "Reading3" FLOAT8))
WHERE sn = NEW.serno;
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
CREATE TRIGGER insert_tg
BEFORE INSERT ON details
FOR EACH ROW EXECUTE PROCEDURE insert_fx();
It returns this error:
ERROR: syntax error at or near "CC1027HCA0GESKN00CC000FT0000"
LINE 6: tb2. serial = 043611007853619CC1027HCA0GESKN00CC000FT...
I think it does not accept characters, it only accepts integers. Maybe the quoting need some modification and I'm not that familiar with pgsql quoting.
I need help to finish my project. I'm stuck on this part.

Answer 1

The immediate cause of the error message is that you concatenated the string NEW.serno without quoting it. To safely fix use format() or quote_literal() or quote_nullable().
...
UPDATE outputtb
SET (reading1, reading2, reading3)
= (SELECT ct.reading1, ct.reading2, ct.reading3
FROM crosstab(
'SELECT serial, t2.readings, t2.value
FROM data t2
JOIN outputtb t1 USING (serial)
WHERE serial = ' || quote_nullable(NEW.serno) || '
ORDER BY 1'
, $$VALUES ('reading1'),('reading2'),('reading3')$$
) ct (serial text, reading1 float8, reading2 float8, reading3 float8))
WHERE sn = NEW.serno;
...
Basics:
Insert text with single quotes in PostgreSQL
In passing I also fixed your incorrect mixed-case identifiers:
Are PostgreSQL column names case-sensitive?
But there are more problems:
newserial has not been declared and is also not used.
outputtb is pointless noise in the query passed to crosstab().
Like #a_horse commented, you shouldn't need an INSERT and an UPDATE, and crosstab() also seems like overkill.
This is a big mess.
Going out on a limb, my educated guess is you want this:
CREATE OR REPLACE FUNCTION insert_fx()
RETURNS TRIGGER AS
$func$
BEGIN
INSERT INTO outputtb (serial, date, judge, reading1, reading2, reading3)
SELECT NEW.serial, NEW.date, NEW.tjudge, ct.*
FROM (SELECT 1) dummy
LEFT JOIN crosstab (
'SELECT serial, readings, value
FROM data
WHERE serial = ' || quote_nullable(NEW.serno) || '
ORDER BY 1'
, $$VALUES ('reading1'),('reading2'),('reading3')$$
) ct (serial text, reading1 float8, reading2 float8, reading3 float8) ON true;
RETURN NEW;
END
$func$ LANGUAGE plpgsql;
The LEFT JOIN to a dummy table prevents losing the INSERT when crosstab() comes up empty.
Which can be simplified to:
CREATE OR REPLACE FUNCTION insert_fx()
RETURNS TRIGGER AS
$func$
BEGIN
INSERT INTO outputtb (serial, date, judge, reading1, reading2, reading3)
SELECT NEW.serial, NEW.date, NEW.tjudge
min(value) FILTER (WHERE readings = 'reading1')
min(value) FILTER (WHERE readings = 'reading2')
min(value) FILTER (WHERE readings = 'reading3')
FROM data
WHERE serial = NEW.serno;
RETURN NEW;
END
$func$ LANGUAGE plpgsql;
Since we aggregate now, a result row is guaranteed, and we don't have to defend against losing it.
Aside:
"serial" is not a reserved word. But it's the name of a common pseudo data-type, so I still wouldn't use it as column name to avoid confusing error situations.