I need to be able to get the value stored inside rec_key.empname when I call this function:
CREATE OR REPLACE FUNCTION public.txt(text)
RETURNS SETOF record
LANGUAGE plpgsql
AS $function$
declare
var_param text;
var_req TEXT;
rec_key record;
cur_key CURSOR FOR Select empname::varchar from employee;
BEGIN
open cur_key;
loop
fetch cur_key into rec_key;
EXIT WHEN NOT FOUND;
var_req :=
'
' || $1 || '
';
return query execute var_req;
end loop;
close cur_key;
END
$function$
;
What do I have to change to get the desired empname when calling the function?
If I call it like this it doesn't work: :(
select * from public.txt('select empid, age::integer,''''''|rec_key.empname|''''''::varchar from employee') as (empid integer, age integer, empname varchar)
To address the question asked:
CREATE OR REPLACE FUNCTION public.txt(_sql text)
RETURNS SETOF record
LANGUAGE plpgsql AS
$func$
DECLARE
_rec record;
BEGIN
FOR _rec IN
SELECT empname::text FROM employee
LOOP
RETURN QUERY EXECUTE _sql
USING _rec.empname;
END LOOP;
END
$func$;
Call:
SELECT * FROM public.txt('SELECT empid, age::integer, $1 AS empname FROM employee')
AS (empid integer, age integer, empname varchar);
The example does not make any sense, though, and all of it could be replaced with a simple query. See my anser to your earlier question:
Doesn't find variable when passing query as parameter
Use the much simpler implicit cursor of a FOR loop. See:
Cursor based records in PostgreSQL
Truncating all tables in a Postgres database
Pass the variable as value with a USING clause. $1 is the symbol to reference the first USING argument. See:
Replace double quotes with single quotes in Postgres (plpgsql)
Related
I have a bytea column in a table that contains a function decode(). What I have done to get the actual data is as follows:
select filename, convert_from(data,'UTF-8') from attachments limit 20; //this returns me decode function
select decode(E'...','hex'); // I am executing the above returned function
The above is fine as long as I have to select one row. But now my requirement is to get more than one result. How can I get the result in single query? I have tried using pl/pgsql
CREATE OR REPLACE FUNCTION get_data(integer, _type anyelement, OUT _result anyelement)
AS
$x$
BEGIN
EXECUTE
'SELECT ' || (select convert_from(data,'UTF-8') as data from attachments limit $1)
INTO _result;
END;
$x$
LANGUAGE plpgsql;
But this works only for single row and single column. What I want is a single query to fetch 2 columns without using pl/pgsql if possible. I am using this query from my Java based web app.
Thanks!
You need procedural code for this, since there is no provision for dynamic statements in SQL.
The following function converts all attachments:
CREATE FUNCTION getemall(
IN v_type anyelement,
OUT v_result anyelement
) RETURNS SETOF anyelement
LANGUAGE plpgsql AS
$$DECLARE
v_stmt text;
BEGIN
FOR v_stmt IN
SELECT convert_from(data,'UTF-8')
FROM attachments
LOOP
EXECUTE v_stmt INTO v_result;
RETURN NEXT;
END LOOP;
END;$$;
This is how I have written the function with few changes
CREATE OR REPLACE FUNCTION getmeall(tName text, fNameCol text, dataCol text,fSize
numeric)
RETURNS TABLE(bdata bytea, fname text) LANGUAGE plpgsql AS
$$DECLARE
v_stmt text;
v_name text;
BEGIN
FOR v_stmt,v_name IN
EXECUTE format('SELECT encode(%s, ''escape''), %s FROM %s
WHERE $1 IS NOT NULL AND $2 IS NOT NULL LIMIT $3'
, dataCol, fNameCol, tName)
USING dataCol, fNameCol, fSize
LOOP
fname:=v_name;
IF strpos(v_stmt,'decode') = 1 THEN
EXECUTE 'SELECT ' || v_stmt INTO bdata;
ELSE
bdata:=v_stmt;
END IF;
RETURN NEXT;
END LOOP;
END;$$;
And finally calling it this way.
select * from getmeall('attachments', '"filename"', '"data"',2)
I'm trying to get a customer id which can be placed in one of ten different tables. I don't want to hard code those table names to find it so I tried postgresql function as follows.
create or replace FUNCTION test() RETURNS SETOF RECORD AS $$
DECLARE
rec record;
BEGIN
select id from schema.table_0201_0228 limit 1 into rec;
return next rec;
select id from schema.table_0301_0331 limit 1 into rec;
return next rec;
END $$ language plpgsql;
select * from test() as (id int)
As I'm not familiar with postgresql function usage, how can I improve the code to replace 'schema.table1' with a variable, loop each table and return the result?
NOTE: table names may change overtime. For example, table_0201_0228 and table_0301_0331 are for February and March respectively.
You need dynamic SQL for that:
create or replace FUNCTION test(p_schema text)
RETURNS table(id int)
AS $$
DECLARE
l_tab record;
l_sql text;
BEGIN
for l_tab in (select schemaname, tablename
from pg_tables
where schemaname = p_schema)
loop
l_sql := format('select id from %I.%I limit 1', l_tab.schemaname, l_tab.tablename);
return query execute l_sql;
end loop;
END $$
language plpgsql;
I made the schema name a parameter, but of course you can hard-code it. As the function is defined as returns table there is no need to specify the column name when using it:
select *
from test('some_schema');
I have some function on PostgreSQL 9.6 returning a cursor (refcursor):
CREATE OR REPLACE FUNCTION public.test_returning_cursor()
RETURNS refcursor
IMMUTABLE
LANGUAGE plpgsql
AS $$
DECLARE
_ref refcursor = 'test_returning_cursor_ref1';
BEGIN
OPEN _ref FOR
SELECT 'a' :: text AS col1
UNION
SELECT 'b'
UNION
SELECT 'c';
RETURN _ref;
END
$$;
I need to write another function in which a temp table is created and all data from this refcursor are inserted to it. But INSERT INTO ... FETCH ALL FROM ... seems to be impossible. Such function can't be compiled:
CREATE OR REPLACE FUNCTION public.test_insert_from_cursor()
RETURNS table(col1 text)
IMMUTABLE
LANGUAGE plpgsql
AS $$
BEGIN
CREATE TEMP TABLE _temptable (
col1 text
) ON COMMIT DROP;
INSERT INTO _temptable (col1)
FETCH ALL FROM "test_returning_cursor_ref1";
RETURN QUERY
SELECT col1
FROM _temptable;
END
$$;
I know that I can use:
FOR _rec IN
FETCH ALL FROM "test_returning_cursor_ref1"
LOOP
INSERT INTO ...
END LOOP;
But is there better way?
Unfortunately, INSERT and SELECT don't have access to cursors as a whole.
To avoid expensive single-row INSERT, you could have intermediary functions with RETURNS TABLE and return the cursor as table with RETURN QUERY. See:
Return a query from a function?
CREATE OR REPLACE FUNCTION f_cursor1_to_tbl()
RETURNS TABLE (col1 text) AS
$func$
BEGIN
-- MOVE BACKWARD ALL FROM test_returning_cursor_ref1; -- optional, see below
RETURN QUERY
FETCH ALL FROM test_returning_cursor_ref1;
END
$func$ LANGUAGE plpgsql; -- not IMMUTABLE
Then create the temporary table(s) directly like:
CREATE TEMP TABLE t1 ON COMMIT DROP
AS SELECT * FROM f_cursor1_to_tbl();
See:
Creating temporary tables in SQL
Still not very elegant, but much faster than single-row INSERT.
Note: Since the source is a cursor only the first call succeeds. Executing the function a second time would return an empty set. You would need a cursor with the SCROLL option and move to the start for repeated calls.
This function does INSERT INTO from refcursor. It is universal for all the tables. The only requirement is that all columns of table corresponds to columns of refcursor by types and order (not necessary by names).
to_json() does the trick to convert any primitive data types to string with double-quotes "", which are later replaced with ''.
CREATE OR REPLACE FUNCTION public.insert_into_from_refcursor(_table_name text, _ref refcursor)
RETURNS void
LANGUAGE plpgsql
AS $$
DECLARE
_sql text;
_sql_val text = '';
_row record;
_hasvalues boolean = FALSE;
BEGIN
LOOP --for each row
FETCH _ref INTO _row;
EXIT WHEN NOT found; --there are no rows more
_hasvalues = TRUE;
SELECT _sql_val || '
(' ||
STRING_AGG(val.value :: text, ',') ||
'),'
INTO _sql_val
FROM JSON_EACH(TO_JSON(_row)) val;
END LOOP;
_sql_val = REPLACE(_sql_val, '"', '''');
_sql_val = TRIM(TRAILING ',' FROM _sql_val);
_sql = '
INSERT INTO ' || _table_name || '
VALUES ' || _sql_val;
--RAISE NOTICE 'insert_into_from_refcursor(): SQL is: %', _sql;
IF _hasvalues THEN --to avoid error when trying to insert 0 values
EXECUTE (_sql);
END IF;
END;
$$;
Usage:
CREATE TABLE public.table1 (...);
PERFORM my_func_opening_refcursor();
PERFORM public.insert_into_from_refcursor('public.table1', 'name_of_refcursor_portal'::refcursor);
where my_func_opening_refcursor() contains
DECLARE
_ref refcursor = 'name_of_refcursor_portal';
OPEN _ref FOR
SELECT ...;
I am call the function but it is returning error that array value must start with "{" or dimension information using
Create or Replace Function get_post_process_info(IN v_esdt_pp character varying[])
Returns setof Record as
$$
Declare
post_processes RECORD;
esdt_value character varying;
v_sdsname character varying[];
v_dimension character varying[];
counter int := 1;
Begin
-- to loop through the array and get the values for the esdt_values
FOR esdt_value IN select * from unnest(v_esdt_pp)
LOOP
-- esdt_values as a key for the multi-dimensional arrays and also as the where clause value
SELECT distinct on ("SdsName") "SdsName" into v_sdsname from "Collection_ESDT_SDS_Def" where "ESDT" = esdt_values;
raise notice'esdt_value: %',esdt_value;
END LOOP;
Return ;
End
$$ Language plpgsql;
Select get_post_process_info(array['ab','bc]);
Your function sanitized:
CREATE OR REPLACE FUNCTION get_post_process_info(v_esdt_pp text[])
RETURNS SETOF record AS
$func$
DECLARE
esdt_value text;
v_sdsname text[];
v_dimension text[];
counter int := 1;
BEGIN
FOR esdt_value IN
SELECT * FROM unnest(v_esdt_pp) t
LOOP
SELECT distinct "SdsName" INTO v_sdsname
FROM "Collection_ESDT_SDS_Def"
WHERE "ESDT" = esdt_value;
RAISE NOTICE 'esdt_value: %', esdt_value;
END LOOP;
END
$func$ Language plpgsql;
Call:
Select get_post_process_info('{ab,bc}'::text[]);
DISTINCT instead of DISTINCT ON, missing table alias, formatting, some cruft, ...
Finally the immediate cause of the error: a missing quote in the call.
The whole shebang can possibly be replaced with a single SQL statement.
But, obviously, your function is incomplete. Nothing is returned yet. Information is missing.
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.