This is a simplified example of what I want to do.
I have a function that returns some valid sql statement as text, based on the input of a integer id. These sql statements always return a boolean value.
create function query_func(_id bigint) returns text as $$
select sql from my_table_of_sql_statements where id = _id;
$$ language sql;
I want to execute these sql statements based on an input id value and return the result as a scalar function.
create or replace function test.ufn_id_exists (_id bigint) returns boolean as $$
declare sql text;
res bool;
begin
sql = query_func(_id);
execute sql into res;
return res;
end;
$$
My question is: is there any way to re-write the second function that doesn't require the intermediate variables 'res' or 'sql'?
You can get away with the sql variable, but I don't think there is a way to get rid of the result variable:
create or replace function test.ufn_id_exists (_id bigint) returns boolean as $$
declare res bool;
begin
execute query_func(_id) into res;
return res;
end;
$$
Related
I'm a beginner in plpgsql and working on a project which requires me to write a function that returns two variables in the form of 2 columns (res,Result). I've done a quite a bit of searching but didn't find answer for the same. The reference to my code is below
CREATE OR REPLACE FUNCTION propID(character varying)
RETURNS SETOF RECORD AS $val$
DECLARE
t_row record;
res BOOLEAN;
result character varying;
value record;
BEGIN
FOR t_row IN SELECT property_id FROM property_table WHERE ward_id::TEXT = $1 LOOP
RAISE NOTICE 'Analyzing %', t_row;
res := false; -- here i'm going to replace this value with a function whos return type is boolean in future
result := t_row.property_id;
return next result; --here i want to return 2 variables (res,result) in the form of two columns (id,value)
END LOOP;
END;
$val$
language plpgsql;
Any help on the above query would be very much appreciated.
Assuming that property_id and ward_id are integers you can achieve your goal in a simple query like this:
select some_function_returning_boolean(property_id), property_id
from property_table
where ward_id = 1; -- input parameter
If you absolutely need a function, it can be an SQL function like
create or replace function prop_id(integer)
returns table (res boolean, id int) language sql
as $$
select some_function_returning_boolean(property_id), property_id
from property_table
where ward_id = $1
$$;
In a plpgsql function you should use return query:
create or replace function prop_id(integer)
returns table (res boolean, id int) language plpgsql
as $$
begin
return query
select some_function_returning_boolean(property_id), property_id
from property_table
where ward_id = $1;
end
$$;
Below is my function, even after having a RETURN statement, but a
query has no destination for result data
error is thrown. Am I missing something?
CREATE OR REPLACE FUNCTION test(ulds character varying)
RETURNS boolean AS
$BODY$
DECLARE
val_result boolean;
BEGIN
select * from regexp_split_to_array('BLK&AAK&AKE', '&');
SET val_result = false;
RETURN val_result;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION test(character varying)
There are more than one issues:
Result of unbind queries is not result of function in Postgres. You need to use INTO clause.
regexp_split_to_array is scalar function, there is not any reason to call this function from SELECT statement. Use SELECT only when you take result of table function, or when you need to read data from relations.
assign statement in plpgsql is based on := symbol. The command SET is used for something different.
the type text is proffered against varchar for function's parameters.
So your code can looks like:
CREATE OR REPLACE FUNCTION test(ulds text)
RETURNS boolean AS $$
DECLARE
result boolean;
target text[];
BEGIN
-- suboptimal, don't do this!!!
SELECT regexp_split_to_array('BLK&AAK&AKE', '&') INTO target;
-- preferred
target := regexp_split_to_array('BLK&AAK&AKE', '&');
result := true;
RETURN result;
END;
$$ LANGUAGE plpgsql;
I am new to PostgreSQL. I have the query:
---------
DO
$$
DECLARE
l_pin INT;
l_pin1 int;
BEGIN
l_pin := 3;
l_pin1 := 4;
select l_pin,l_pin1;
END;
$$
LANGUAGE PLPGSQL;
--------------------------
from above query am getting an error as
ERROR: query has no destination for result data
HINT: If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT: PL/pgSQL function inline_code_block line 9 at SQL statement
SQL state: 42601
I need to get the values of l_pin and l_pin1 as output.
What you have there is a DO statement, not a "query" nor a "function". DO statements cannot return anything at all.
How to perform a select query in a DO block?
The displayed error is because you cannot call SELECT in a plpgsql code block without assigning the result. To actually return values from a plpgsql function, use some form of RETURN (explicitly or implicitly).
As minimal example:
CREATE OR REPLACE FUNCTION foo(OUT l_pin int, OUT l_pin1 int)
RETURNS record AS -- RETURNS record is optional because of OUT parameters
$func$
BEGIN
l_pin := 3;
l_pin1 := 4;
RETURN; -- RETURN is optional here because of OUT parameters
END
$func$ LANGUAGE plpgsql;
SELECT * FROM foo();
Related:
Can I make a plpgsql function return an integer without using a variable?
SELECT or PERFORM in a PL/pgSQL function
Returning from a function with OUT parameter
First you can create a new type that can hold multiple values:
CREATE TYPE type_name AS (l_pin INTEGER, l_pin1 INTEGER);
Then you can do something like:
CREATE OR REPLACE FUNCTION function_name()
RETURNS type_name AS $$
DECLARE
result type_name;
BEGIN
/* Code that puts those values into type_name object
i.e.
result.l_pin := 3;
result.l_pin1 := 4;
*/
return result ;
END
$$ language plpgsql
I am trying to call a function inside of a trigger in postgres. Basically I have a function,
c.check_level(bigint, integer)
which returns a boolean value.
I would like to call this function inside of a trigger as follows:
CREATE OR REPLACE FUNCTION c.check_level_tg()
RETURNS trigger AS
$BODY$
DECLARE
parent_id int8;
level int;
result bool;
begin
parent_id := NEW.fk_parent;
level := NEW.level;
select * from c.check_category_level(parent_id, level) as result;
if (result) then
return (NEW);
else
return(NULL);
end if;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION c.check_category_level_tg()
OWNER TO postgres;
When I try to put data in the table on which this trigger resides, I get an error:
"ERROR: query has no destination for result data HINT: If you want to discard the results of a SELECT, use PERFORM instead. CONTEXT: PL/pgSQL function".
The function c.check_level works properly when run in isolation.
Change
select * from c.check_category_level(parent_id, level) as result;
into:
SELECT c.check_category_level(parent_id, level) INTO result;
I've got a pretty simple function defined like so:
CREATE OR REPLACE FUNCTION create_new_order(....) RETURNS integer AS
$BODY$
BEGIN
PERFORM add_points_to_usage(client_id_p, date_in_p, total_points_p);
INSERT INTO orders (...) VALUES (...)
RETURNING ident;
END;
$BODY$ LANGUAGE plpgsql;
Where I'm struggling is how to actually RETURN the value stored in the ident field back via the RETURNING clause. I've tried setting the value to a variable but that either doesn't work or I'm just messing up the syntax.
You're missing the variable declaration, the INTO clause and the final RETURN:
CREATE OR REPLACE FUNCTION create_new_order(....) RETURNS integer AS
$BODY$
DECLARE
var_ident int;
BEGIN
PERFORM add_points_to_usage(client_id_p, date_in_p, total_points_p);
INSERT INTO orders (...) VALUES (...)
RETURNING ident INTO var_ident;
RETURN var_ident;
END;
$BODY$ LANGUAGE plpgsql;