I am migrating stored procedure from SQL SERVER to POSTGRESQL. I should return table. But, I have following problem:
IF ROWSTATE = 'L' THEN
return TABLE A;
ELSIF ROWSTATE = 'C' THEN
return TABLE B;
END IF
How to do it, using function in POSTGRESQL?
You have to create a function that RETURNS TABLE with the columns expected from tables a and b, e.g:
CREATE OR REPLACE FUNCTION myfunc(rowstate text)
RETURNS TABLE (ret_col1 text, ret_col2 text) AS $$
BEGIN
IF $1='L' THEN
RETURN QUERY SELECT cola1, cola2 FROM a;
ELSEIF $1='C' THEN
RETURN QUERY SELECT colb1, colb2 FROM b;
END IF;
END;
$$ LANGUAGE plpgsql;
Demo: db<>fiddle
Related
Need Output from table with in clause in PostgreSQL
I tried to make loop or ids passed from my code. I did same to update the rows dynamically, but for select I m not getting values from DB
CREATE OR REPLACE FUNCTION dashboard.rspgetpendingdispatchbyaccountgroupidandbranchid(
IN accountgroupIdCol numeric(8,0),
IN branchidcol character varying
)
RETURNS void
AS
$$
DECLARE
ArrayText text[];
i int;
BEGIN
select string_to_array(branchidcol, ',') into ArrayText;
i := 1;
loop
if i > array_upper(ArrayText, 1) then
exit;
else
SELECT
pd.branchid,pd.totallr,pd.totalarticle,pd.totalweight,
pd.totalamount
FROM dashboard.pendingdispatch AS pd
WHERE
pd.accountgroupid = accountgroupIdCol AND pd.branchid IN(ArrayText[i]::numeric);
i := i + 1;
end if;
END LOOP;
END;
$$ LANGUAGE 'plpgsql' VOLATILE;
There is no need for a loop (or PL/pgSQL actually)
You can use the array directly in the query, e.g.:
where pd.branchid = any (string_to_array(branchidcol, ','));
But your function does not return anything, so obviously you won't get a result.
If you want to return the result of that SELECT query, you need to define the function as returns table (...) and then use return query - or even better make it a SQL function:
CREATE OR REPLACE FUNCTION dashboard.rspgetpendingdispatchbyaccountgroupidandbranchid(
IN accountgroupIdCol numeric(8,0),
IN branchidcol character varying )
RETURNS table(branchid integer, totallr integer, totalarticle integer, totalweight numeric, totalamount integer)
AS
$$
SELECT pd.branchid,pd.totallr,pd.totalarticle,pd.totalweight, pd.totalamount
FROM dashboard.pendingdispatch AS pd
WHERE pd.accountgroupid = accountgroupIdCol
AND pd.branchid = any (string_to_array(branchidcol, ',')::numeric[]);
$$
LANGUAGE sql
VOLATILE;
Note that I guessed the data types for the columns of the query based on their names. You have to adjust the line with returns table (...) to match the data types of the select columns.
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 have a postgres function that I'd like to return the result of a query, but I'd like it to return nothing if that query matches more than 1 record.
So, something like:
CREATE OR REPLACE FUNCTION myFunc(_a text, _b text)
RETURNS yy
LANGUAGE plpgsql
STABLE
PARALLEL SAFE
AS $$
BEGIN
RETURN QUERY
SELECT *
FROM yy
WHERE a = x
AND b = y;
END;
$$;
Except, it should return nothing if that query matches more than 1 record.
CREATE OR REPLACE FUNCTION myFunc(_a text, _b text)
RETURNS SETOF yy -- To be able to return "nothing"
LANGUAGE plpgsql
STABLE
PARALLEL SAFE
AS $$
DECLARE
result yy;
BEGIN
SELECT *
INTO STRICT result -- STRICT allows to check that exactly one row returned
FROM yy
WHERE a = x
AND b = y;
RETURN NEXT result; -- RETURN NEXT - return yet another row for "RETURNS SETOF" function
EXCEPTION
WHEN no_data_found OR too_many_rows THEN -- When no data or more then one rows
RETURN; -- Nothing to return, just exit
END;
$$;
i guess this can help you out.
CREATE OR REPLACE FUNCTION database.myFunction(
IN text,IN text)
RETURNS TABLE(firstField, secondField, lastField) AS
$BODY$
--sql string is the variable containing the final sql code
declare sql_string text;
declare regs numeric;
begin
--this is what happens in case count<1
sql_string = 'select 0,0,0';
--now we count them
regs = (select count(firstField) from mytable where a=b)::numeric;
--if >=1, then whe get the whole data
if (regs>=1) then
sql_string = 'select firstField,secondField, lastField from mytable where a=b';
end if;
--and return to you...
return query EXECUTE sql_string;
end;
I have a simple mission is inserting huge MD5 values into tables (partitioned table), and have created a trigger and also a trigger function to instead of INSERT operation. And in function I checked the first two characters of NEW.md5 to determine which table should be inserted.
DECLARE
tb text;
BEGIN
IF TG_OP = 'INSERT' THEN
tb = 'samples_' || left(NEW.md5, 2);
EXECUTE(format('INSERT INTO %s VALUES (%s);', tb, NEW.*)); <- WRONG
END IF;
RETURN NULL;
END;
The question is how to concat the NEW.* into the SQL statement?
Best with the USING clause of EXECUTE:
CREATE FUNCTION foo ()
RETURNS trigger AS
$func$
BEGIN
IF TG_OP = 'INSERT' THEN
EXECUTE format('INSERT INTO %s SELECT $1.*'
, 'samples_' || left(NEW.md5, 2);
USING NEW;
END IF;
RETURN NULL;
END
$func$ LANGUAGE plpgsql;
And EXECUTE does not require parentheses.
And you are aware that identifiers are folded to lower case unless quoted where necessary (%I instead of %s in format()).
More details:
INSERT with dynamic table name in trigger function
How to dynamically use TG_TABLE_NAME in PostgreSQL 8.2?
I have the code:
DECLARE
cliente_cursor CURSOR FOR SELECT * FROM cliente;
cliente cliente.id_clie%TYPE;
nom cliente.nom_clie%TYPE;
BEGIN
OPEN cliente_cursor;
FETCH cliente_cursor INTO cliente, nom;
But I cannot run it. The following error appears:
ERROR: syntax error at or near "cliente"
LINE 3: cliente cliente.id_clie% TYPE;
^
I have the table "cliente" which has:
I want to create a cursor that shows only the content of the columns: id_clie, nom_clie of the previous table.
I have also used:
create or replace function facturas_cliente()
returns table (a int, b character varying(40))
language plpgsql as $$
declare
x cliente%rowtype ;
cliente_cursor cursor for select id_clie, nom_clie from cliente
order by id_clie;
begin
for x in cliente_cursor loop
return next x;
end loop;
end $$;
But I get the error:
ERROR: RETURN NEXT can not have parameters in a function with OUT parameters
LINE 9: return next x;
^
What am I doing wrong?
First issue is strange. I tested on PostgreSQL 9.5 (but same code should to work on 9.2 and newer):
CREATE TABLE cliente(id_clie int, tel_clie varchar(15), dir_clie varchar(15));
DO $$
DECLARE
cliente_cursor CURSOR FOR SELECT * FROM cliente;
cliente cliente.id_clie%TYPE;
tel cliente.tel_clie%TYPE;
BEGIN
OPEN cliente_cursor;
END;
$$;
And it works without any issue. It looks like some mistyped error.
Second issue is clear. When function has a OUT variables or is declared as TABLE function, then RETURN NEXT has to be without expression. Returned composite value is based on actual context of OUT variables (columns declared in TABLE clause are OUT variables too). Your code should to be:
create or replace function facturas_cliente()
returns table (a int, b character varying(40))
language plpgsql as $$
declare
cliente_cursor cursor for select id_clie, nom_clie
from cliente
order by id_clie;
r record;
begin
for r in cliente_cursor -- a,b ~ OUT var declared in TABLE() clause
loop
a := r.id_clie; b := r.nom_clie;
return next; -- not: return next x;
end loop;
end $$;
This code can be reduced in PL/pgSQL two ways:
use a SQL function
create or replace function facturas_cliente()
returns table (a int, b character varying(40))
language sql as $$
select id_clie, nom_clie from cliente order by id_clie;
$$ language plpgsql;
use a RETURN QUERY statement in plpgsql:
create or replace function facturas_cliente()
returns table (a int, b character varying(40))
language sql as $$
BEGIN
RETURN QUERY SELECT id_clie, nom_clie
FROM cliente
ORDER BY id_clie;
RETURN;
END;
$$ language plpgsql;
Attention: these function can block a SQL optimizer if you use it in some complex query than trivial. Personally I don't like it. Use a view instead. It works like you need and there is no risk with optimization.
CREATE VIEW facturas_cliente
AS SELECT id_clie, nom_clie
FROM cliente
ORDER BY id_clie;