I have a stored procedure in the form of:
CREATE FUNCTION schema.myfunction(id uuid)
RETURNS TABLE (report jsonb) AS $$
BEGIN
RETURN QUERY WITH rows AS (
SELECT
jsonb_build_object(
'rowNumber', ROW_NUMBER(),
'id', t.id
) AS row
FROM schema.table t
WHERE t.id = id
)
SELECT
COALESCE(jsonb_agg(r.row), '[]') AS report
FROM rows r;
END;
$$ LANGUAGE plpgsql STRICT STABLE SECURITY DEFINER;
GRANT EXECUTE ON FUNCTION schema.myfunction(
uuid
) TO schema_user;
How can I get the same result but running this function as a transaction? Without creating the function itself. Something in the form of:
db.transaction(async (trx) => {
const {
rows: [result],
} = await trx.raw(
'<supposed code here, maybe>;',
[id]
);
res.status(200).json(result);
}
Is it possible?
I tried with DO block but I can't return anything from it. Any guidance on the right direction would help tremendously.
Related
I have a query similar to this:
SELECT COALESCE(
(SELECT jsonb_agg(s) FROM ((SELECT column FROM my_table)) AS s),
'[]'::jsonb
);
which returns all rows in json format:
[
{
"column": 1,
},
{
"column": 2
}
]
And if there are no rows, it returns a empty array instead of null.
I want to re-use this, but it would quickly become a mess to type out the whole thing everywhere. That's why I trying to create this as_json function:
-- DOESNT WORK
CREATE FUNCTION as_json(query ???)
RETURNS jsonb
LANGUAGE sql
AS $$
SELECT COALESCE((SELECT jsonb_agg(s) FROM query AS s), '[]'::jsonb);
$$;
If I could make it work, using it would be as simple as
as_json(SELECT column FROM my_table)
Can I achieve something like that in postgresql?
It's actually quite easy to write something similar to query_to_xml()
create or replace function query_to_jsonb(p_query text, p_include_nulls boolean default false)
returns jsonb
as
$$
declare
l_result jsonb;
l_sql text;
begin
if p_include_nulls then
l_sql := 'select jsonb_agg(to_jsonb(dt)) from ('||p_query||') as dt';
else
l_sql := 'select jsonb_agg(jsonb_strip_nulls(to_jsonb(dt))) from ('||p_query||') as dt';
end if;
execute l_sql
into l_result;
return coalesce(l_result, '{}');
end;
$$
language plpgsql;
Then you can return the result of a query (string) as a JSON value, e.g.
select query_to_jsonb('SELECT column FROM my_table');
To remove NULL values from the result, use:
select query_to_jsonb('select col1, col2 from some_table', true);
I have this question, I was doing some migration from SQL Server to PostgreSQL 12.
The scenario, I am trying to accomplish:
The function should have a RETURN Statement, be it with SETOF 'tableType' or RETURN TABLE ( some number of columns )
The body starts with a count of records, if there is no record found based on input parameters, then simply Return Zero (0), else, return the entire set of record defined in the RETURN Statement.
The Equivalent part in SQL Server or Oracle is: They can just put a SELECT Statement inside a Procedure to accomplish this. But, its a kind of difficult in case of PostgreSQL.
Any suggestion, please.
What I could accomplish still now - If no record found, it will simply return NULL, may be using PERFORM, or may be selecting NULL as column name for the returning tableType columns.
I hope I am clear !
What I want is something like -
============================================================
CREATE OR REPLACE FUNCTION public.get_some_data(
id integer)
RETURNS TABLE ( id_1 integer, name character varying )
LANGUAGE 'plpgsql'
AS $BODY$
DECLARE
p_id alias for $1;
v_cnt integer:=0;
BEGIN
SELECT COUNT(1) FROM public.exampleTable e
WHERE id::integer = e.id::integer;
IF v_cnt= 0 THEN
SELECT 0;
ELSE
SELECT
a.id, a.name
public.exampleTable a
where a.id = p_id;
END;
$BODY$;
If you just want to return a set of a single table, using returns setof some_table is indeed the easiest way. The most basic SQL function to do that would be:
create function get_data()
returns setof some_table
as
$$
select *
from some_table;
$$
language sql;
PL/pgSQL isn't really necessary to put a SELECT statement into a function, but if you need to do other things, you need to use RETURN QUERY in a PL/pgSQL function:
create function get_data()
returns setof some_table
as
$$
begin
return query
select *
from some_table;
end;
$$
language plpgsql;
A function as exactly one return type. You can't have a function that sometimes returns an integer and sometimes returns thousands of rows with a dozen columns.
The only thing you could do, if you insist on returning something is something like this:
create function get_data()
returns setof some_table
as
$$
begin
return query
select *
from some_table;
if not found then
return query
select (null::some_table).*;
end if;
end;
$$
language plpgsql;
But I would consider the above an extremely ugly and confusing (not to say stupid) solution. I certainly wouldn't let that pass through a code review.
The caller of the function can test if something was returned in the same way I implemented that ugly hack: check the found variable after using the function.
One more hack to get as close as possible to what you want. But I will repeat what others have told you: You cannot do what you want directly. Just because MS SQL Server lets you get away poor coding does not mean Postgres is obligated to do so. As the link by #a_horse_with_no_name implies converting code is easy, once you migrate how you think about the problem in the first place. The closest you can get is return a tuple with a 0 id. The following is one way.
create or replace function public.get_some_data(
p_id integer)
returns table ( id integer, name character varying )
language plpgsql
as $$
declare
v_at_least_one boolean = false;
v_exp_rec record;
begin
for v_exp_rec in
select a.id, a.name
from public.exampletable a
where a.id = p_id
union all
select 0,null
loop
if v_exp_rec.id::integer > 0
or (v_exp_rec.id::integer = 0 and not v_at_least_one)
then
id = v_exp_rec.id;
name = v_exp_rec.name;
return next;
v_at_least_one = true;
end if;
end loop ;
return;
end
$$;
But that is still just a hack and assumes there in not valid row with id=0. A much better approach would by for the calling routing to check what the function returns (it has to do that in one way or another anyway) and let the function just return the data found instead of making up data. That is that mindset shift. Doing that you can reduce this function to a simple select statement:
create or replace function public.get_some_data2(
p_id integer)
returns table ( id integer, name character varying )
language sql strict
as $$
select a.id, a.name
from public.exampletable a
where a.id = p_id;
$$;
Or one of the other solutions offered.
I'm using Postgresql and trying to have a select statement in a function to call out. At the moment the call gives me zero results
CREATE OR REPLACE FUNCTION f_all_male_borrowers
(
OUT p_given_names varchar(60),
OUT p_family_name varchar(60),
OUT p_gender_code integer
)
RETURNS SETOF record as $body$
declare body text;
BEGIN
SELECT into p_given_names,p_family_name, p_gender_code
borrower.given_names, borrower.family_name, gender.gender_code
FROM BORROWER
INNER join gender on borrower.gender_code=gender.gender_code
WHERE borrower.gender_code = '1';
RETURN ;
END;
$body$ LANGUAGE plpgsql;
Call to function:
select * from f_all_male_borrowers()
What is missing, or what am I doing wrong here?
Thank you
CREATE OR REPLACE FUNCTION f_all_male_borrowers
(
OUT p_given_names varchar(60),
OUT p_family_name varchar(60),
OUT p_gender_code integer
)
RETURNS SETOF record as
$body$
SELECT into p_given_names,p_family_name, p_gender_code
borrower.given_names, borrower.family_name, gender.gender_code
FROM BORROWER
INNER join gender on borrower.gender_code=gender.gender_code
WHERE borrower.gender_code = '1';
$body$
LANGUAGE sql VOLATILE
COST 100
ROWS 1000;
ALTER FUNCTION f_all_male_borrowers()
OWNER TO postgres;
Try this and then call :
select * from f_all_male_borrowers();
Before doing that you need to check whether your query have result or not !!
After creating function then:
Got to Functions->Right click your function(ie,f_all_male_borrowers())-> Scripts->Select Script ->Then run it.
If it returns result then your procedure is correct.
Is it possible to execute an update conditionally if a column exists?
For instance, I may have a column in a table and if that column exists I want that update executed, otherwise, just skip it (or catch its exception).
You can do it inside a function. If you don't want to use the function later you can just drop it afterwards.
To know if a column exists in a certain table, you can try to fetch it using a select(or a perform, if you're gonna discard the result) in information_schema.columns.
The query bellow creates a function that searches for a column bar in a table foo, and if it finds it, updates its value. Later the function is run, then droped.
create function conditional_update() returns void as
$$
begin
perform column_name from information_schema.columns where table_name= 'foo' and column_name = 'bar';
if found then
update foo set bar = 12345;
end if;
end;
$$ language plpgsql;
select conditional_update();
drop function conditional_update();
With the following table as example :
CREATE TABLE mytable (
idx INT
,idy INT
);
insert into mytable values (1,2),(3,4),(5,6);
you can create a custom function like below to update:
create or replace function fn_upd_if_col_exists(_col text,_tbl text,_val int) returns void as
$$
begin
If exists (select 1
from information_schema.columns
where table_schema='public' and table_name=''||_tbl||'' and column_name=''||_col||'' ) then
execute format('update mytable set '||_col||'='||_val||'');
raise notice 'updated';
else
raise notice 'column %s doesn''t exists on table %s',_col,_tbl;
end if;
end;
$$
language plpgsql
and you can call this function like:
select fn_upd_if_col_exists1('idz','mytable',111) -- won't update raise "NOTICE: column idz deosnt exists on table mytables"
select fn_upd_if_col_exists1('idx','mytable',111) --will upadate column idx with value 1111 "NOTICE: updated"
I'm trying to create a PL/pgSQL function, which should populate a temporary table and then return all rows from it (it will be a join later), but I don't know which return type to specify for it:
create or replace function pref_daily_misere() returns void as $BODY$
begin
create temporary table temp_best (id varchar not null) on commit drop;
insert into temp_best (id) select id from pref_money where
yw = to_char(current_timestamp - interval '1 week', 'IYYY-IW')
order by money desc limit 10;
select id from temp_best;
end;
$BODY$ language plpgsql;
The statements above work on their own, but give me the error
# select pref_daily_misere();
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 "pref_daily_misere" line 7 at SQL statement
when I try to call it in my PostgreSQL 8.4.11 database.
This is probably because I have wrongly specified the returns void above, but I don't know which return type to use instead and omitting the return type is a compile error.
You want to use a setof varchar return type and then return query ... inside the function. From the fine manual:
39.6.1.2. RETURN NEXT and RETURN QUERY
RETURN NEXT expression;
RETURN QUERY query;
RETURN QUERY EXECUTE command-string [ USING expression [, ... ] ];
When a PL/pgSQL function is declared to return SETOF sometype, the procedure to follow is slightly different. In that case, the individual items to return are specified by a sequence of RETURN NEXT or RETURN QUERY commands, and then a final RETURN command with no argument is used to indicate that the function has finished executing.
I think you want something more like this:
create or replace function pref_daily_misere() returns setof varchar as $BODY$
begin
create temporary table temp_best (id varchar not null) on commit drop;
insert into temp_best (id)
select id
from pref_money
where yw = to_char(current_timestamp - interval '1 week', 'IYYY-IW')
order by money
desc limit 10;
return query select id from temp_best;
return;
end;
$BODY$ language plpgsql;
However, the temp table is pointless here:
Note: The current implementation of RETURN NEXT and RETURN QUERY stores the entire result set before returning from the function, as discussed above.
So PostgreSQL is computing the entire result set and caching it by itself. You could do this:
create or replace function pref_daily_misere() returns setof varchar as $BODY$
begin
return query
select id
from pref_money
where yw = to_char(current_timestamp - interval '1 week', 'IYYY-IW')
order by money
desc limit 10;
return;
end;
$BODY$ language plpgsql;
I'm pretty sure the temp table is going to be dropped at the end of your function anyway so you should get rid of it.