I have searched and could not find an open post regarding this topic:
I'm working with stored procedures in PostgreSQL and I'm currently being asked to create one that will collect certain information from a publisher based on the only parameter passed, their publishercode.
This code is in the existing table as a "character" type and as such I'm passing it the same and calling the function with that same type input, but I'm only obtaining a "NULL" value from my input and I'm not sure why.
This is my code:
CREATE OR REPLACE FUNCTION uspGetPubStatsMAC (pubcode publisher.publishercode%TYPE) -- Publisher Code
RETURNS text AS
$$
DECLARE PubCode publisher.publishercode%TYPE;
PubName text;
NumOfAuth int;
NumOfPubBooks int;
HiValBook text;
NumHiValBook int;
TotNumHiValBook int;
BEGIN
-- Get the publisher's name from the given code
RAISE NOTICE 'Code: (%)', pubcode;
SELECT publishername INTO PubName
FROM publisher
WHERE publishercode = pubcode;
RAISE NOTICE 'Name: (%)', PubName;
-- check if a publisher exists with the given code
IF ( PubName is null )
THEN
RAISE NOTICE 'No publisher exists with the given code (%)', pubcode;
RETURN (-1);
END IF;
RAISE NOTICE 'Current Statistics of the publisher (%)', pubcode;
RAISE NOTICE ' The Name of the Publisher: (%)', trim (trailing ' ' from PubName);
SELECT count(distinct a.authornum) INTO NumOfAuth
FROM publisher p, book b, wrote w, author a
WHERE p.publishercode = b.publishercode
and b.bookcode = w.bookcode;
RAISE NOTICE ' The number of distinct authors who have written book(s) for this publisher: (%)', NumOfAuth;
END;
$$ language plpgsql;
SELECT uspGetPubStatsMAC('AH');
Where 'AH' is the code corresponding to publisher Arkham House in my table. Any idea of what I'm doing wrong?
You have at least two errors in your code:
pubcode is the parameter passed in to the function. Then you declare a local PubCode variable. Remove that declaration.
Your function should RETURN some text value representing PUBstatsMAC when it succeeds. Currently you only return -1 if there is an error. At that point you should RAISE an error with an appropriate message and forget about a return value, otherwise a bad return value may get cascaded into other code.
Furthermore, after a SELECT ... INTO ... statement you should test for the FOUND internal variable rather than a NULL value in a local variable:
IF NOT FOUND THEN
RAISE 'No publisher exists with the given code (%)', pubcode;
END IF;
And your query on number of distinct authors will give a bad result because you are missing a join clause on table author.
Then, you have a bunch of unused local variables declared.
Lastly, it is bad practice to return your information from a function in a bunch of RAISE NOTICE statements.
Thanks a lot for your feedback! I will test some of these fixes.
With respect to the return of -1 that is a requirement by the teacher. He wants a -1 if an error occurred at run time and a 0 if not. Hence why the output is formatted as raise notices. Also a requirement.
The extra local variables are there because that is an unfinished portion of the entire procedure code.
I tried what you suggested though and it worked like a charm. The extra declaration of PubCode was causing the problem.
Thanks so much!!!
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'm having trouble with writing a procedure in PostgreSQL. I can create the procedure, yet when i try to execute i get an error.The error i get
ERROR: "v_all_atts" is not a known variable
the query is:
CREATE OR REPLACE FUNCTION rebuild_views_with_extra_atts()
RETURNS VOID AS $$
DECLARE
v_all_atts varchar(4000);
BEGIN
CREATE OR REPLACE FUNCTION add_column(p_table text, p_column text,p_category text) RETURNS VOID AS $nothing$
declare
v_column_exists bigint := false ;
BEGIN
SELECT
string_agg( CASE WHEN owner='alarm' THEN 'ai' WHEN owner='fault' THEN 'fi'
END ||'.'||lower(alias) , ', ' ORDER BY owner, alias) AS string
INTO STRICT
v_all_atts
FROM
extra_attribute_cfg
WHERE
owner NOT LIKE 'virtual' and enable = true and v_column_exists = true;
IF LENGTH(v_all_atts) is not null THEN
v_all_atts := ', '||v_all_atts;
END IF;
v_view:= q'#
CREATE OR REPLACE VIEW alarm_view AS
SELECT
fi.fault_id, ai.alarm_id,
#'||v_all_atts||q'#
FROM
alarm ai
INNER JOIN fault fi
ON fi.fault_id = ai.fault_id
#';
EXECUTE v_view;
END;
$nothing$ language plpgsql;
end;
$$ LANGUAGE plpgsql;
I have taken a long look at Postgres documentation and cannot find what is wrong and didn't find any answer to this specific situation
Your rebuild_views_with_extra_atts() function is creating the add_column() function.
add_column() uses the v_all_atts variable, but it doesn't exist in that function, it exists only in the rebuild_views_with_extra_atts() function.
To resolve this, it really depends on what you're trying to do. If that variable should exist in the add_column() function, then declare it in there. If you're trying to use the value of v_all_atts when creating add_column() (e.g. so that the content of the function's body is dependent on the value of that variable), then you really need to use dynamic sql to generate a TEXT version of the CREATE OR REPLACE ... code, then EXECUTE it.
I have a trigger working in postgres, it allows a view to become updateable.
CREATE OR REPLACE FUNCTION actualizaIDConductor() RETURNS
TRIGGER AS '
BEGIN
RAISE NOTICE ''Working'';
SELECT COUNT(*) INTO bool
FROM Infotrenes
WHERE cod_empleado = OLD.cod_empleado;
RAISE NOTICE ''bool = %'', bool;
--The id belongs to the view
IF (bool > 0) THEN
UPDATE ...; --This works fine
ELSE
RAISE EXCEPTION ''ERROR: ...'';
END IF;
RETURN NEW;
END;
' LANGUAGE 'plpgsql';
The "problem" comes when I want to update a row that doesn't belong to the view. Instead of printing my "ERROR:..." message it just displays UPDATE 0. It doesn't even display the "Working" notice.
Is this some sort of the manager optimization or am I doing something wrong? Can I somehow print the message?
This code should not to work - there are undeclared variable bool (secondary - it's wrong name due same named data type). So this code should not to work ever, and should not to raise a notice 'working'.
I have a postgresql function / stored proc that does the following:
1. calls another function and saves the value into a variable.
2. executes another sql statement using the value I got from step one as an argument.
My problem is that the query is not returning any data. No errors are returned either.
I'm just new to postgresql so I don't know the best way to debug... but I added a RAISE NOTICE command right after step 1, like so:
SELECT INTO active_id get_widget_id(widget_desc);
RAISE NOTICE 'Active ID is:(%)', active_id;
In the "Messages" section of the pgadmin3 screen, I see the debug message with the data:
NOTICE: Active ID is:(2)
I'm wondering whether or not the brackets are causing the problem for me.
Here's the sql I'm trying to run in step 2:
SELECT d.id, d.contact_id, d.priority, cp.contact
FROM widget_details d, contact_profile cp, contact_type ct
WHERE d.rule_id=active_id
AND d.active_yn = 't'
AND cp.id=d.contact_id
AND cp.contact_type_id=ct.id
AND ct.name = 'email'
Order by d.priority ASC
You'll notice that in my where clause I am referencing the variable "active_id".
I know that this query should return at least one row because when i run a straight sql select (vs using this function) and substitute the value 2 for the variable "active_id", I get back the data I'm looking for.
Any suggetions would be appreciated.
Thanks.
EDIT 1:
Here's the full function definition:
CREATE TYPE custom_return_type AS (
widgetnum integer,
contactid integer,
priority integer,
contactdetails character varying
);
CREATE OR REPLACE FUNCTION test(widget_desc integer)
RETURNS SETOF custom_return_type AS
$BODY$
DECLARE
active_id integer;
rec custom_return_type ;
BEGIN
SELECT INTO active_id get_widget_id(widget_desc);
RAISE NOTICE 'Active ID is:(%)', active_id;
FOR rec IN
SELECT d.id, d.contact_id, d.priority, cp.contact
FROM widget_details d, contact_profile cp, contact_type ct
WHERE d.rule_id=active_id
AND d.active_yn = 't'
AND cp.id=d.contact_id
AND cp.contact_type_id=ct.id
AND ct.name = 'email'
Order by d.priority ASC
LOOP
RETURN NEXT rec;
END LOOP;
END
$BODY$
That's several levels of too-complicated (edit: as it turns out that Erwin already explained to you last time you posted the same thing). Start by using RETURNS TABLE and RETURN QUERY:
CREATE OR REPLACE FUNCTION test(fmfm_number integer)
RETURNS TABLE (
widgetnum integer,
contactid integer,
priority integer,
contactdetails character varying
) AS
$BODY$
BEGIN
RETURN QUERY SELECT d.id, d.contact_id, d.priority, cp.contact
FROM widget_details d, contact_profile cp, contact_type ct
WHERE d.rule_id = get_widget_id(widget_desc)
AND d.active_yn = 't'
AND cp.id=d.contact_id
AND cp.contact_type_id=ct.id
AND ct.name = 'email'
Order by d.priority ASC;
END
$BODY$ LANGUAGE plpgsql;
at which point it's probably simple enough to be turned into a trivial SQL function or even a view. Hard to be sure, since the function doesn't make tons of sense as written:
You never use the parameter fmfm_number anywhere; and
widget_desc is never defined
so this function could never run. Clearly you haven't shown us the real source code, but some kind of "simplified" code that doesn't match the code you're really having issues with.
There is a difference between:
SELECT INTO ...
[http://www.postgresql.org/docs/current/interactive/sql-selectinto.html]
and
SELECT select_expressions INTO [STRICT] target FROM ...;
[http://www.postgresql.org/docs/current/interactive/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-ONEROW]
I think you want:
SELECT get_widget_id(widget_desc) INTO active_id;
I have a function that is used as an INSERT trigger. This function deletes rows that would conflict with [the serial number in] the row being inserted. It works beautifully, so I'd really rather not debate the merits of the concept.
DECLARE
re1 feeds_item.shareurl%TYPE;
BEGIN
SELECT regexp_replace(NEW.shareurl, '/[^/]+(-[0-9]+\.html)$','/[^/]+\\1') INTO re1;
RAISE NOTICE 'DELETEing rows from feeds_item where shareurl ~ ''%''', re1;
DELETE FROM feeds_item where shareurl ~ re1;
RETURN NEW;
END;
I would like to add to the NOTICE an indication of how many rows are affected (aka: deleted). How can I do that (using LANGUAGE 'plpgsql')?
UPDATE:
Base on some excellent guidance from "Chicken in the kitchen", I have changed it to this:
DECLARE
re1 feeds_item.shareurl%TYPE;
num_rows int;
BEGIN
SELECT regexp_replace(NEW.shareurl, '/[^/]+(-[0-9]+\.html)$','/[^/]+\\1') INTO re1;
DELETE FROM feeds_item where shareurl ~ re1;
IF FOUND THEN
GET DIAGNOSTICS num_rows = ROW_COUNT;
RAISE NOTICE 'DELETEd % row(s) from feeds_item where shareurl ~ ''%''', num_rows, re1;
END IF;
RETURN NEW;
END;
For a very robust solution, that is part of PostgreSQL SQL and not just plpgsql you could also do the following:
with a as (DELETE FROM feeds_item WHERE shareurl ~ re1 returning 1)
select count(*) from a;
You can actually get lots more information such as:
with a as (delete from sales returning amount)
select sum(amount) from a;
to see totals, in this way you could get any aggregate and even group and filter it.
In Oracle PL/SQL, the system variable to store the number of deleted / inserted / updated rows is:
SQL%ROWCOUNT
After a DELETE / INSERT / UPDATE statement, and BEFORE COMMITTING, you can store SQL%ROWCOUNT in a variable of type NUMBER. Remember that COMMIT or ROLLBACK reset to ZERO the value of SQL%ROWCOUNT, so you have to copy the SQL%ROWCOUNT value in a variable BEFORE COMMIT or ROLLBACK.
Example:
BEGIN
DECLARE
affected_rows NUMBER DEFAULT 0;
BEGIN
DELETE FROM feeds_item
WHERE shareurl = re1;
affected_rows := SQL%ROWCOUNT;
DBMS_OUTPUT.
put_line (
'This DELETE would affect '
|| affected_rows
|| ' records in FEEDS_ITEM table.');
ROLLBACK;
END;
END;
I have found also this interesting SOLUTION (source: http://markmail.org/message/grqap2pncqd6w3sp )
On 4/7/07, Karthikeyan Sundaram wrote:
Hi,
I am using 8.1.0 postgres and trying to write a plpgsql block. In that I am inserting a row. I want to check to see if the row has been
inserted or not.
In oracle we can say like this
begin
insert into table_a values (1);
if sql%rowcount > 0
then
dbms.output.put_line('rows inserted');
else
dbms.output.put_line('rows not inserted');
end if; end;
Is there something equal to sql%rowcount in postgres? Please help.
Regards skarthi
Maybe:
http://www.postgresql.org/docs/8.2/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-ONEROW
Click on the link above, you'll see this content:
37.6.6. Obtaining the Result Status There are several ways to determine the effect of a command. The first method is to use the GET
DIAGNOSTICS command, which has the form:
GET DIAGNOSTICS variable = item [ , ... ];This command allows
retrieval of system status indicators. Each item is a key word
identifying a state value to be assigned to the specified variable
(which should be of the right data type to receive it). The currently
available status items are ROW_COUNT, the number of rows processed by
the last SQL command sent down to the SQL engine, and RESULT_OID, the
OID of the last row inserted by the most recent SQL command. Note that
RESULT_OID is only useful after an INSERT command into a table
containing OIDs.
An example:
GET DIAGNOSTICS integer_var = ROW_COUNT; The second method to
determine the effects of a command is to check the special variable
named FOUND, which is of type boolean. FOUND starts out false within
each PL/pgSQL function call. It is set by each of the following types
of statements:
A SELECT INTO statement sets FOUND true if a row is assigned, false if
no row is returned.
A PERFORM statement sets FOUND true if it produces (and discards) a
row, false if no row is produced.
UPDATE, INSERT, and DELETE statements set FOUND true if at least one
row is affected, false if no row is affected.
A FETCH statement sets FOUND true if it returns a row, false if no row
is returned.
A FOR statement sets FOUND true if it iterates one or more times, else
false. This applies to all three variants of the FOR statement
(integer FOR loops, record-set FOR loops, and dynamic record-set FOR
loops). FOUND is set this way when the FOR loop exits; inside the
execution of the loop, FOUND is not modified by the FOR statement,
although it may be changed by the execution of other statements within
the loop body.
FOUND is a local variable within each PL/pgSQL function; any changes
to it affect only the current function.
I would to share my code (I had this idea from Roelof Rossouw):
CREATE OR REPLACE FUNCTION my_schema.sp_delete_mytable(_id integer)
RETURNS integer AS
$BODY$
DECLARE
AFFECTEDROWS integer;
BEGIN
WITH a AS (DELETE FROM mytable WHERE id = _id RETURNING 1)
SELECT count(*) INTO AFFECTEDROWS FROM a;
IF AFFECTEDROWS = 1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
EXCEPTION WHEN OTHERS THEN
RETURN 0;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;