The below is the snippet where I pass a cursor as input paramter in Oracle.
And Im trying to convert the same to EntepriseDB.
create or replace FUNCTION FUNCTION_1
(
p_source IN SYS_REFCURSOR
)
is
TYPE row_ntt
IS
TABLE OF VARCHAR2(32767);
v_rows row_ntt;
begin
---
LOOP
FETCH p_source BULK COLLECT
INTO v_rows LIMIT 1000
;
FOR i IN 1 .. v_rows.COUNT
LOOP
-- Will do something here
END LOOP;
EXIT WHEN p_source%NOTFOUND;
END LOOP;
END;
it's called in the below way in Oracle:
SELECT
*
FROM
TABLE ( function_1(CURSOR(select col1 from tbl)));
Now after migration
I changed like below
create or replace FUNCTION FUNCTION_1
(
p_source IN SYS_REFCURSOR
)
is
TYPE row_ntt
IS
TABLE OF VARCHAR2(32767);
v_rows row_ntt;
begin
---
select unnest(p_source) into v_rows;
FOR i IN 1 .. v_rows.COUNT
LOOP
-- Will do something here
END LOOP;
END;
Im calling in the below way in EntepriseDB/Postgresql
SELECT
*
FROM
TABLE (function_1(ARRAY(
SELECT
col1 from table)));
Im getting below error at assigning the value to v_rows.
ERROR: cannot assign non-table type to a table
Please help me in making unnest as table type so that it inserts into v_rows. or else if there is a way I can use sysrefcursor in EnterpriseDB is also fine. Please let me know how to call in ENtepriseDB when sysrefcursor is used. Thanks!!
Related
I have a function that uses RECORD to temporarily store the data. I can use it - it's fine. My problem is that I can't hardcode columns I need to get from the RECORD. I must do it dynamically. Something line:
DECLARE
r1 RECORD;
r2 RECORD;
BEGIN
for r1 in Select column_name
from columns_to_process
where process_now = True
loop
for r2 in Select *
from my_data_table
where whatever
loop
-----------------------------
here I must call column by its name that is unknown at design time
-----------------------------
... do something with
r2.(r1.column_name)
end loop;
end loop;
END;
Does anyone know how to do it?
best regards
M
There is no need to select the all the qualifying rows and compute the total in a loop. Actually when working with SQL try to drop the word loop for your vocabulary; instead just use sum(column_name) in the select. The issue here is that you do not know what column to sum when the query is written, and all structural components(table names, columns names, operators, etc) must be known before submitting. You cannot use a variable for a structural component - in this case a column name. To do that you must use dynamic sql - i.e. SQL statement built by the process. The following accomplishes that: See example here.
create or replace function sum_something(
the_something text -- column name
, for_id my_table.id%type -- my_table.id
)
returns numeric
language plpgsql
as $$
declare
k_query_base constant text :=
$STMT$ Select sum(%I) from my_table where id = %s; $STMT$;
l_query text;
l_sum numeric;
begin
l_query = format(k_query_base, the_something, for_id);
raise notice E'Rumming Statememt:\n %',l_query; -- for prod raise Log
execute l_query into l_sum;
return l_sum;
end;
$$;
Well, after some time I figured out that I could use temporary table instead of RECORD. Doing so gives me all advantages of using dynamic queries so I can call any column by its name.
DECLARE
_my_var bigint;
BEGIN
create temporary table _my_temp_table as
Select _any, _column, _you, _need
from _my_table
where whatever = something;
execute 'Select ' || _any || ' from _my_temp_table' into _my_var;
... do whatever
END;
However I still believe that there should be a way to call records field by it's name.
I am trying to create the query as a string and execute that in PostgreSQL 10.
As far as I know, I can use the EXECUTE command to execute my query from a defined string.
Unfortunately, I have got an error: SQL Error [42601]: ERROR: syntax error at or near "execute"
Below is my code:
drop table if exists delinquent;
create table delinquent
(
report_date date
,account_id text
)
;
INSERT INTO delinquent VALUES('2019-07-23', 'a1234');
INSERT INTO delinquent VALUES('2019-07-23', 'b5679');
--------------
drop table if exists output1;
create temp table output1
(
report_date date
,account_id text
)
;
--------------
do $$
declare table_name text := 'delinquent';
begin
truncate table output1;
insert into output1
execute concat('select * from ',table_name);
end; $$;
select * from output1;
Anybody has an idea on what is wrong and what to do about it?
Many thanks,
You need to run the complete INSERT statement as dynamic SQL. And to build dynamic SQL, using format() is highly recommended to properly deal with identifiers and literals:
do $$
declare
table_name text := 'delinquent';
some_value text := 'a1234';
begin
truncate table output1;
execute format('insert into output1 select * from %I where some_column = %L',
table_name, some_value);
end; $$;
select *
from output1;
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 am trying to log changes, if any were made to a table, but I am stuck when trying to loop through column names. I am receiving a "array value must start with "{" ... line 6 at FOR over SELECT rows" error. I do not understand why this is happening.. The function compiles ok but running an update gives that error.
CREATE TABLE test(x varchar(50))
CREATE OR REPLACE FUNCTION testF()
RETURNS trigger
AS $$
DECLARE
col varchar[255]; //don't know if this is the right variable type to use
BEGIN
IF OLD.* IS DISTINCT FROM NEW.* THEN
FOR col in SELECT column_name FROM information_schema.columns WHERE table_schema = TG_TABLE_SCHEMA AND table_name = TG_TABLE_NAME LOOP
INSERT INTO test(x) VALUES(col||'oldValue:'||OLD.col||'newValue:'||NEW.col); //I want to put the name and the old and new values in a varchar field
END LOOP;
END IF;
RETURN NULL;
END $$ LANGUAGE plpgsql;
CREATE TRIGGER testT AFTER UPDATE
ON "triggerTable" FOR EACH ROW EXECUTE PROCEDURE testF();
to get at the columns of OLD or NEW by name you'll have to use exec an a bunch of typecasts.
something like this:
execute '('||quote_literal(NEW::text)||'::'||quote_ident(pg_typeof(NEW))||
').'||quote_ident(col)||'::text';
this may get you imprecise values for some floats
Im new to writing stored functions in postgresql and in general . I'm trying to write onw with an input parameter and return a set of results stored in a temporary table.
I do the following in my function .
1) Get a list of all the consumers and store their id's stored in a temp table.
2) Iterate over a particular table and retrieve values corresponding to each value from the above list and store in a temp table.
3)Return the temp table.
Here's the function that I've tried to write by myself ,
create or replace function getPumps(status varchar) returns setof record as $$ (setof record?)
DECLARE
cons_id integer[];
i integer;
temp table tmp_table;--Point B
BEGIN
select consumer_id into cons_id from db_consumer_pump_details;
FOR i in select * from cons_id LOOP
select objectid,pump_id,pump_serial_id,repdate,pumpmake,db_consumer_pump_details.status,db_consumer.consumer_name,db_consumer.wenexa_id,db_consumer.rr_no into tmp_table from db_consumer_pump_details inner join db_consumer on db_consumer.consumer_id=db_consumer_pump_details.consumer_id
where db_consumer_pump_details.consumer_id=i and db_consumer_pump_details.status=$1--Point A
order by db_consumer_pump_details.consumer_id,pump_id,createddate desc limit 2
END LOOP;
return tmp_table
END;
$$
LANGUAGE plpgsql;
However Im not sure about my approach and whether im right at the points A and B as I've marked in the code above.And getting a load of errors while trying to create the temporary table.
EDIT: got the function to work ,but I get the following error when I try to run the function.
ERROR: array value must start with "{" or dimension information
Here's my revised function.
create temp table tmp_table(objectid integer,pump_id integer,pump_serial_id varchar(50),repdate timestamp with time zone,pumpmake varchar(50),status varchar(2),consumer_name varchar(50),wenexa_id varchar(50),rr_no varchar(25));
select consumer_id into cons_id from db_consumer_pump_details;
FOR i in select * from cons_id LOOP
insert into tmp_table
select objectid,pump_id,pump_serial_id,repdate,pumpmake,db_consumer_pump_details.status,db_consumer.consumer_name,db_consumer.wenexa_id,db_consumer.rr_no from db_consumer_pump_details inner join db_consumer on db_consumer.consumer_id=db_consumer_pump_details.consumer_id where db_consumer_pump_details.consumer_id=i and db_consumer_pump_details.status=$1
order by db_consumer_pump_details.consumer_id,pump_id,createddate desc limit 2;
END LOOP;
return query (select * from tmp_table);
drop table tmp_table;
END;
$$
LANGUAGE plpgsql;
AFAIK one can't declare tables as variables in postgres. What you can do is create one in your funcion body and use it thourough (or even outside of function). Beware though as temporary tables aren't dropped until the end of the session or commit.
The way to go is to use RETURN NEXT or RETURN QUERY
As for the function result type I always found RETURNS TABLE to be more readable.
edit:
Your cons_id array is innecessary, just iterate the values returned by select.
Also you can have multiple return query statements in a single function to append result of the query to the result returned by function.
In your case:
CREATE OR REPLACE FUNCTION getPumps(status varchar)
RETURNS TABLE (objectid INTEGER,pump_id INTEGER,pump_serial_id INTEGER....)
AS
$$
BEGIN
FOR i in SELECT consumer_id FROM db_consumer_pump_details LOOP
RETURN QUERY(
SELECT objectid,pump_id,pump_serial_id,repdate,pumpmake,db_consumer_pump_details.status,db_consumer.consumer_name,db_consumer.wenexa_id,db_consumer.rr_no FROM db_consumer_pump_details INNER JOIN db_consumer ON db_consumer.consumer_id=db_consumer_pump_details.consumer_id
WHERE db_consumer_pump_details.consumer_id=i AND db_consumer_pump_details.status=$1
ORDER BY db_consumer_pump_details.consumer_id,pump_id,createddate DESC LIMIT 2
);
END LOOP;
END;
$$
edit2:
You probably want to take a look at this solution for groupwise-k-maximum problem as that's exactly what you're dealing with here.
it might be easier to just return a table (or query)
CREATE FUNCTION extended_sales(p_itemno int)
RETURNS TABLE(quantity int, total numeric) AS $$
BEGIN
RETURN QUERY SELECT quantity, quantity * price FROM sales
WHERE itemno = p_itemno;
END;
$$ LANGUAGE plpgsql;
(copied from postgresql docs)