I work with Postgres9.5. I have an example which successfully returns the results of a cursor as a string (concatenation of rows):
Here is the example:
CREATE OR REPLACE FUNCTION get_doctor_appoint()
RETURNS TEXT AS $$
DECLARE
Names TEXT DEfault '';
rec_appoint RECORD;
doctor_appoint cursor
FOR SELECT * FROM appointments
where doctorAMKA = (SELECT doctoramka FROM doctor WHERE username='foo#bar.net')
AND t>'2017-4-6 00:00:00' AND t<'2017-5-6 00:00:00';
BEGIN
OPEN doctor_appoint;
LOOP
FETCH doctor_appoint INTO rec_appoint;
EXIT WHEN NOT FOUND;
Names:=Names||','||rec_appoint.t||':'||rec_appoint.patientamka;
END LOOP;
CLOSE doctor_appoint;
RETURN Names;
END; $$
LANGUAGE plpgsql;
I would like to return the results as a table but haven't found an example that does that.
You declare the function as RETURNS SETOF text.
For every row you want to return, use RETURN NEXT text_value;.
To end function execution, use RETURN or drop out at the bottom end of the function.
Related
I am new to plpgsql, and I am excercising cursor.
I have following simple code,
create or replace function func_cursor_2()
returns setof numeric as $$
declare
cursor1 CURSOR for select empno,ename, job from emp;
r record;
begin
open cursor1;
loop
fetch from cursor1 into r;
exit when not found;
return next r.empno;
end loop;
close cursor1;
end;
$$ language plpgsql;
select func_cursor_2()
With fetch from cursor1 into r,
It looks to me that I am fetching the result rows one by one?
Is there way to specify 100 rows for one fetch from cursor?
Why bother with a cursor at all. This can be done in 1 statement.
create or replace function func_cursor_2()
returns setof numeric
language sql
as $$
select empno
from emp
limit 100;
$$;
However, the above will not return consistent results. To generate consistent you will need to add order by empno and perhaps offset depending on your exact needs.
Note: Not Tested.
in my loop I would like to return the result of an SQL query here:
select mybd.service_offer_01 (rec.id_v2, $ 2, $ 3);
Do you have an idea ?
Thank you
CREATE OR REPLACE FUNCTION select_price(param1 TEXT, param2 TEXT,param3 TEXT)
RETURNS TABLE (
id_v2 TEXT
prix prix_type
)
AS $$
do
$$
declare
rec record;
begin
for rec in select regexp_split_to_table($1,',') as id_v2
loop
select mybd.service_offre_01(rec.id_v2,$2,$3);
end loop;
end;
$$
Your code cannot to work from more reasons:
Syntax - the nesting DO statement is absolutely useless, and more - it block any result. There is not possibility to return anything from DO statement.
The result of plpgsql is realized by RETURN statement. For table function, like your, you should to use RETURN NEXT or RETURN QUERY. RETURN NEXT sends one row to output, RETURN QUERY sends a result of some query. It is well documented. Please, read doc - https://www.postgresql.org/docs/current/plpgsql.html. The lot of pattern are described here - and documentation reading is only work for few hours. This is good investment :)
So your code can looks like (I have not detailed info about function service_offre_01):
CREATE OR REPLACE FUNCTION select_price(param1 TEXT, param2 TEXT,param3 TEXT)
RETURNS TABLE (id_v2 TEXT, prix prix_type)
AS $$
DECLARE rec record;
BEGIN
FOR rec IN SELECT regexp_split_to_table($1,',') AS id_v2
LOOP
RETURN QUERY SELECT * FROM mybd.service_offre_01(rec.id_v2,$2,$3);
END LOOP;
END;
$$;
I have a sample stored procedure where in I have to use a table for multiple operations. I want to declare the table name as a constant and then re-use it wherever required. Below is the sample code which i wrote:
CREATE OR REPLACE FUNCTION get_data()
RETURNS void AS
$func$
DECLARE
table_name_a CONSTANT TEXT = asp.monitoring_bookmark_original;
cursor_file CURSOR FOR
select distinct filename,systemuid from table_name_a;
cursor_data CURSOR FOR
select * from table_name_a where filename = v_filename and systemuid=v_systemuid order by mindatetime, maxdatetime;
BEGIN
--open the file cursor
//logic goes here
END;
$func$
LANGUAGE plpgsql;
When I try to run this procedure I am getting error:
ERROR: missing FROM-clause entry for table "asp"
LINE 1: SELECT asp.monitoring_bookmark_original
What is wrong in this code? How do I correct this?
Well you can use dynamic SQL, but realize dynamic SQL often adds way more complexity. Good when really needed but should be avoided when possible. The following shows what would be needed for what you want to do. Is not having to type the table name for each SQL statement worth the additional trouble?
create or replace function get_data()
returns void as
$func$
declare
table_name_a constant text = 'asp.monitoring_bookmark_original';
file_cursor text = 'select distinct filename,systemuid from %i';
file_ref refcursor;
file_rec record;
data_cursor text =$stmt$select * from %i where filename = '%s' and systemuid= '%s' order by mindatetime, maxdatetime$stmt$;
data_ref refcursor;
data_rec record;
begin
--open the file cursor
open file_ref for execute format(file_cursor,table_name_a);
loop
fetch next from file_ref into file_rec;
exit when not found;
-- and extending from what the second query inplies
open data_ref for execute format(data_cursor,table_name_a,file_rec.filename,file_rec.systemid);
loop
fetch next from data_ref into data_rec;
exit when not found;
--//logic goes here
end loop;
end loop ;
end;
$func$
language plpgsql;
I'm trying to create a function to get a field value from multiple tables in my database. I made script like this:
CREATE OR REPLACE FUNCTION get_all_changes() RETURNS SETOF RECORD AS
$$
DECLARE
tblname VARCHAR;
tblrow RECORD;
row RECORD;
BEGIN
FOR tblrow IN SELECT tablename FROM pg_catalog.pg_tables WHERE schemaname='public' LOOP /*FOREACH tblname IN ARRAY $1 LOOP*/
RAISE NOTICE 'r: %', tblrow.tablename;
FOR row IN SELECT MAX("lastUpdate") FROM tblrow.tablename LOOP
RETURN NEXT row;
END LOOP;
END LOOP;
END
$$
LANGUAGE 'plpgsql' ;
SELECT get_all_changes();
But it is not working, everytime it shows this error
tblrow.tablename" not defined in line "FOR row IN SELECT MAX("lastUpdate") FROM tblrow.tablename LOOP"
Your inner FOR loop must use the FOR...EXECUTE syntax as shown in the manual:
FOR target IN EXECUTE text_expression [ USING expression [, ... ] ] LOOP
statements
END LOOP [ label ];
In your case something along this line:
FOR row IN EXECUTE 'SELECT MAX("lastUpdate") FROM ' || quote_ident(tblrow.tablename) LOOP
RETURN NEXT row;
END LOOP
The reason for this is explained in the manual somewhere else:
Oftentimes you will want to generate dynamic commands inside your PL/pgSQL functions, that is, commands that will involve different tables or different data types each time they are executed. PL/pgSQL's normal attempts to cache plans for commands (as discussed in Section 39.10.2) will not work in such scenarios. To handle this sort of problem, the EXECUTE statement is provided[...]
Answer to your new question (mislabeled as answer):
This can be much simpler. You do not need to create a table just do define a record type.
If at all, you would better create a type with CREATE TYPE, but that's only efficient if you need the type in multiple places. For just a single function, you can use RETURNS TABLE instead :
CREATE OR REPLACE FUNCTION get_all_changes(text[])
RETURNS TABLE (tablename text
,"lastUpdate" timestamp with time zone
,nums integer) AS
$func$
DECLARE
tblname text;
BEGIN
FOREACH tblname IN ARRAY $1 LOOP
RETURN QUERY EXECUTE format(
$f$SELECT '%I', MAX("lastUpdate"), COUNT(*)::int FROM %1$I
$f$, tblname)
END LOOP;
END
$func$ LANGUAGE plpgsql;
A couple more points:
Use RETURN QUERY EXECUTE instead of the nested loop. Much simpler and faster.
Column aliases would only serve as documentation, those names are discarded in favor of the names declared in the RETURNS clause (directly or indirectly).
Use format() with %I to replace the concatenation with quote_ident() and %1$I to refer to the same parameter another time.
count() usually returns type bigint. Cast the integer, since you defined the column in the return type as such: count(*)::int.
Thanks,
I finally made my script like:
CREATE TABLE IF NOT EXISTS __rsdb_changes (tablename text,"lastUpdate" timestamp with time zone, nums bigint);
CREATE OR REPLACE FUNCTION get_all_changes(varchar[]) RETURNS SETOF __rsdb_changes AS /*TABLE (tablename varchar(40),"lastUpdate" timestamp with time zone, nums integer)*/
$$
DECLARE
tblname VARCHAR;
tblrow RECORD;
row RECORD;
BEGIN
FOREACH tblname IN ARRAY $1 LOOP
/*RAISE NOTICE 'r: %', tblrow.tablename;*/
FOR row IN EXECUTE 'SELECT CONCAT('''|| quote_ident(tblname) ||''') AS tablename, MAX("lastUpdate") AS "lastUpdate",COUNT(*) AS nums FROM ' || quote_ident(tblname) LOOP
/*RAISE NOTICE 'row.tablename: %',row.tablename;*/
/*RAISE NOTICE 'row.lastUpdate: %',row."lastUpdate";*/
/*RAISE NOTICE 'row.nums: %',row.nums;*/
RETURN NEXT row;
END LOOP;
END LOOP;
RETURN;
END
$$
LANGUAGE 'plpgsql' ;
Well, it works. But it seems I can only create a table to define the return structure instead of just RETURNS SETOF RECORD. Am I right?
Thanks again.
I have the following script that I want output to the screen from.
CREATE OR REPLACE FUNCTION randomnametest() RETURNS integer AS $$
DECLARE
rec RECORD;
BEGIN
FOR rec IN SELECT * FROM my_table LOOP
SELECT levenshtein('mystring',lower('rec.Name')) ORDER BY levenshtein;
END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;
I want to get the output of the levenshein() function in a table along with the rec.Name. How would I do that? Also, it is giving me an error about the line where I call levenshtein(), saying that I should use perform instead.
Assuming that you want to insert the function's return value and the rec.name into a different table. Here is what you can do (create the table new_tab first)-
SELECT levenshtein('mystring',lower(rec.Name)) AS L_val;
INSERT INTO new_tab (L_val, rec.name);
The usage above is demonstrated below.
I guess, you can use RAISE INFO 'This is %', rec.name; to view the values.
CREATE OR REPLACE FUNCTION randomnametest() RETURNS integer AS $$
DECLARE
rec RECORD;
BEGIN
FOR rec IN SELECT * FROM my_table LOOP
SELECT levenshtein('mystring',lower(rec.Name))
AS L_val;
RAISE INFO '% - %', L_val, rec.name;
END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;
Note- the FROM clause is optional in case you select from a function in a select like netxval(sequence_name) and don't have any actual table to select from i.e. like SELECT nextval(sequence_name) AS next_value;, in Oracle terms it would be SELECT sequence_name.nextval FROM dual; or SELECT function() FROM dual;. There is no dual in postgreSQL.
I also think that the ORDER BY is not necessary since my assumption would be that your function levenshtein() will most likely return only one value at any point of time, and hence wouldn't have enough data to ORDER.
If you want the output from a plpgsql function like the title says:
CREATE OR REPLACE FUNCTION randomnametest(_mystring text)
RETURNS TABLE (l_dist int, name text) AS
$BODY$
BEGIN
RETURN QUERY
SELECT levenshtein(_mystring, lower(t.name)), t.name
FROM my_table t
ORDER BY 1;
END;
$$ LANGUAGE plpgsql;
Declare the table with RETURNS TABLE.
Use RETURN QUERY to return records from the function.
Avoid naming conflicts between column names and OUT parameters (from the RETURNS TABLE clause) by table-qualifying column names in queries. OUT parameters are visible everywhere in the function body.
I made the string to compare to a parameter to the function to make this more useful.
There are other ways, but this is the most effective for the task. You need PostgreSQL 8.4 or later.
For a one-time use I would consider to just use a plain query (= function body without the RETURN QUERY above).