The title might be a little confusing but I will try explaining here better.
What I want to achieve is:
Create a table with 3 columns (so far so good):
CREATE TABLE StatisticCounter
(
statisticID NUMBER GENERATED ALWAYS as IDENTITY (START with 1000 INCREMENT by 1),
statistikname varchar(255),
counter integer
);
Create a way to call (function, procedure, trigger or something. I will call it function for now) that will increment counter with 1 based on statistikname or statisticid.
The restriction here being: said statistic is an SQL script ran through a cockpit file with a little bit of a different syntax than regular sql (in: out: select, WHERE with variables). I want to put a function or something in this cockpit file, that will run each time the script is run. Which will auto increment the number of times the statistic has been used.
I have no idea what I need (function, procedure, trigger or anything else) and this is why I am writing it a bit vague.
EDIT: I tried with merge but I always get the WHEN NOT MATCHED result executed. Without CAST its the same.
merge into StatisticCounter stc using
CAST((select 1000 id from dual)AS INTEGER) val on (stc.statisticid=val.id)
when matched then
UPDATE StatisticCounter SET counter = counter + 1;
when not matched then
select * from dual;
I found an answer on my own after going through a lot of functions and procedures.
Create table;
Create function;
Call function in file.
The important thing here is that the outside _cockpit file that executes the SQL goes through all OUT parameters for each line the statistic returns as result. This makes the counter go wild - no way to catch END of statistic or beginning. So I made a second _cockpit with only 1 result and attach it to the statistic I want to count.
CREATE TABLE UDX_Table_StatisticCounter(statisticID INTEGER,
StatistikName varchar2(256 char), counter integer);
CREATE OR REPLACE FUNCTION UDX_FUNC_StatisticCounter(datainput IN
VARCHAR2) RETURN VARCHAR2 IS PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
UPDATE UDX_Table_StatisticCounter SET counter = counter +1 WHERE statisticID=datainput;
COMMIT;
RETURN 'done'; END UDX_FUNC_StatisticCounter;
Related
as I described on the title, I want to write a trigger that defines to add a new staff by all giving attributes except ID, I want to trigger generate and insert it automatically. How can I do that?
I've written a code like below in PL/SQL, but it's including the sequence and I couldn't find how can I get the current max ID of my staff with using the sequence, so could you please help me, with or without using the sequence?
CREATE SEQUENCE BEFORE_INSERTING START WITH 1000 INCREMENT BY 1;
CREATE OR REPLACE TRIGGER NEW_ID_BEFORE_INSERTING
BEFORE INSERT ON STAFF
FOR EACH ROW
BEGIN
:NEW.STAFF_ID := BEFORE_INSERTING.nextval;
END;
/
By the way, this code works fine but as you see it's starting from 1000.
Perhaps you can use something like the following to find the maximum value for STAFF_ID and then redefine the sequence based on that value:
DECLARE
nMax_staff_id NUMBER;
BEGIN
SELECT MAX(STAFF_ID)
INTO nMax_staff_id
FROM STAFF;
EXECUTE IMMEDIATE 'DROP SEQUENCE BEFORE_INSERTING';
EXECUTE IMMEDIATE 'CREATE SEQUENCE BEFORE_INSERTING START WITH ' ||
nMax_staff_id + 1 || ' INCREMENT BY 1';
END;
You only need to run the above once, just to get the sequence reset. After that the trigger will use the sequence to obtain each STAFF_ID value. Note that there are other ways to redefine a sequence's value, but here we'll do The Simplest Thing That Could Possibly Work, which is to drop the sequence and then recreate it with the new starting value.
Best of luck.
in order to find the max STAFF_ID you need the below select:
select max(STAFF_ID) from STAFF;
Once you have the highest STAFF_ID you can re-create the sequence as desired.
In any case you can increment a sequence like so:
ALTER SEQUENCE seq_name INCREMENT BY 1;
I hope that helps!
Please don't hesitate to leave a comment for any further clarifications.
Ted.
Using the sequence guarantees uniqueness of STAFF_ID but does not guarantee no gaps in assigning STAFF_ID. You might end up with STAFF_ID like 100, 101, 103, 106..
First, get the max(STAFF_ID) while the system is not running. Something like
select max(staff_id) from staff;
Then, create the sequence to start from the max staff_id. Something like
create sequence staff_sequence start with <max_id> + 1 increment by 1 nocache;
"NOCACHE" minimizes the chance of having gaps in the staff_id assigned
After, use the trigger that you created to get the nextval from the seuqnece
Note the following:
- Once a sequence is invoked for nextval, that number dispatched cannot be returned to the sequnece
- Any cached sequence values will be lost if oracle database was shutdown
If your requirement is not to have gaps between staff_ids, then sequence might not be used.
Using Postgres 9.4, I have 2 tables streams and comment_replies. I am trying to do is update the streams.comments count each time a new comment_replies is inserted to keep track of the number of comments a particular stream has. I am not getting any errors but when I try to create a new comment it gets ignored.
This is how I am setting up my trigger. stream_id is a foreign key, so every stream_id will correspond to a streams.id which is the primary key of the streams table. I have been looking at this example: Postgres trigger function, but haven't been able to get it to work.
CREATE TABLE comment_replies (
id serial NOT NULL PRIMARY KEY,
created_on timestamp without time zone,
comments text,
profile_id integer,
stream_id integer
);
The trigger function:
CREATE OR REPLACE FUNCTION "Comment_Updates"()
RETURNS trigger AS
$BODY$BEGIN
update streams set streams.comments=streams.comments+1
where streams.id=comment_replies_streamid;
END$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
And the trigger:
CREATE TRIGGER comment_add
BEFORE INSERT OR UPDATE
ON comment_replies
FOR EACH ROW
EXECUTE PROCEDURE "Comment_Updates"();
How can I do this?
There are multiple errors. Try instead:
CREATE OR REPLACE FUNCTION comment_update()
RETURNS trigger AS
$func$
BEGIN
UPDATE streams s
SET streams.comments = s.comments + 1
-- SET comments = COALESCE(s.comments, 0) + 1 -- if the column can be NULL
WHERE s.id = NEW.streamid;
RETURN NEW;
END
$func$ LANGUAGE plpgsql;
CREATE TRIGGER comment_add
BEFORE INSERT OR UPDATE ON comment_replies -- on UPDATE, too? Really?
FOR EACH ROW EXECUTE PROCEDURE comment_update();
You need to consider DELETE as well if that is possible. Also if UPDATE can change stream_id. But why increase the count for every UPDATE? This looks like another error to me.
It's a syntax error to table-qualify the target column in the SET clause of UPDATE.
You need to return NEW in a BEFORE trigger unless you want to cancel the INSERT / UPDATE.
Or you make it an AFTER trigger, which would work for this, too.
You need to reference NEW for the stream_id of the current row (which is automatically visible inside the trigger function.
If streams.comments can be NULL, use COALESCE.
And rather use unquoted, legal, lower-case identifiers.
I want to write a Postgres SQL trigger that will basically find if a number appears in a column 5 or more times. If it appears a 5th time, I want to throw an exception. Here is how the table looks:
create table tab(
first integer not null constraint pk_part_id primary key,
second integer constraint fk_super_part_id references bom,
price integer);
insert into tab values(1,NULL,100), (2,1,50), (3,1,30), (4,2,20), (5,2,10), (6,3,20);
Above are the original inserts into the table. My trigger will occur upon inserting more values into the table.
Basically if a number appears in the 'second' column more than 4 times after inserting into the table, I want to raise an exception. Here is my attempt at writing the trigger:
create function check() return trigger as '
begin
if(select first, second, price
from tab
where second in (
select second from tab
group by second
having count(second) > 4)
) then
raise exception ''Error, there are more than 5 parts.'';
end if;
return null;
end
'language plpgsql;
create trigger check
after insert or update on tab
for each row execute procedure check();
Could anyone help me out? If so that would be great! Thanks!
CREATE FUNCTION trg_upbef()
RETURN trigger as
$func$
BEGIN
IF (SELECT count(*)
FROM tab
WHERE second = NEW.second ) > 3 THEN
RAISE EXCEPTION 'Error: there are more than 5 parts.';
END IF;
RETURN NEW; -- must be NEW for BEFORE trigger
END
$func$ LANGUAGE plpgsql;
CREATE TRIGGER upbef
BEFORE INSERT OR UPDATE ON tab
FOR EACH ROW EXECUTE procedure trg_upbef();
Major points
Keyword is RETURNS, not RETURN.
Use the special variable NEW to refer to the newly inserted / updated row.
Use a BEFORE trigger. Better skip early in case of an exception.
Don't count everything for your test, just what you need. Much faster.
Use dollar-quoting. Makes your live easier.
Concurrency:
If you want to be absolutely sure, you'll have to take an exclusive lock on the table before counting. Else, concurrent inserts / updates might outfox each other under heavy concurrent load. While this is rather unlikely, it's possible.
I am relatively new to postgresql and battling my way to get familiarized with it. I had run in to an error while writing a new pl/sql function. ERROR: type "ordered_parts" does not exist
CREATE OR REPLACE FUNCTION get_ordered_parts(var_bill_to integer)
RETURNS SETOF ordered_parts AS
$BODY$
declare
var_ordered_id record;
var_part ordered_parts;
begin
for var_ordered in select order_id from view_orders where bill_to = var_bill_to
loop
for var_part select os.po_num,os.received,os.customer_note,orders.part_num,orders.description,orders.order_id,orders.remaining_quantity from (select vli.part_num,vli.description,vli.order_id,vli.quantity - vli.quantity_shipped as remaining_quantity from view_line_items as vli where vli.order_id in (select order_id from view_orders where bill_to = var_bill_to and order_id = var_ordered.order_id) and vli.quantity - vli.quantity_shipped > 0)as orders left join order_sales as os on orders.order_id = os.order_id
then
-- Then we've found a leaf part
return next var_part;
end if;
end loop;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE
COST 100
ROWS 1000;
ALTER FUNCTION get_ordered_parts(integer) OWNER TO postgres;
just note - your code is perfect example how don't write stored procedure ever. For some longer results it can be extremely slow. Minimally two cycles can be joined to one, or better, you can use just only one RETURN QUERY statement. Next issue is zero formatting of embedded SQL - good length of line is between 70 and 100 chars - writing long SQL statement to one line going to zero readability and maintainability code.
Relation database is not array, and any query has some cost, so don't use nested FOR if you really don't need it. I am sorry for offtopic.
The error message is telling you that you have declared the return type of your function to be SETOF ordered_parts, but it doesn't know what kind of thing ordered_parts is. Within your Declare block you also have a variable declared as this same type (var_part ordered_parts).
If you had a table or view called ordered_parts, then its "row type" would be automatically created as a type, but this is not the case here. if you just want to use an arbitrary row from a result set, you can just use the generic type record.
So in this case your function should say RETURNS SETOF record, and your Declare block var_part record.
Bonus tip: rather than looping over the result of your query and running RETURN NEXT on each row, you can use RETURN QUERY to throw the whole result set into the returned set in one go. See this Postgres manual page.
how can you select the same sequence twice in one query?
I have googled this and just cant get an answer.
Just to be clear, this is what I need, example :
select seq.nextval as v1, seq.nextval as v2 from dual (I know that doesn't work)
I have tried UNION as well, Just cant get my head around it.
If you always need exactly two values, you could change the sequence to increment by 2:
alter sequence seq increment by 2;
and then select the current value and its successor:
select seq.nextval,
seq.nextval + 1
from dual;
Not pretty, but it should do the job.
UPDATE
Just to clarify: the ALTER SEQUENCE should be issued only once in a lifetime, not once per session!
The Answer by Frank has a downside:
You cannot use it in transactional system, because the ALTER SEQUENCE commits any pending DML.
The Answer of Sean only pulls the sequence once.
As I understand, you want to pull two values.
As an alternative to Seans solution, you could also select two times from .nextval, due ORACLE gives you the same value twice.
I'd prefer wrapping up the sequence in a procedure.
This tricks oracle to pulling the sequence twice.
CREATE or replace FUNCTION GetSeq return number as
nSeq NUMBER;
begin
select seq.nextval into nSeq from dual;
return nSeq;
end;
/
If you need this generically, maybe you'd like:
CREATE or replace FUNCTION GetSeq(spSeq in VARCHAR2) return number as
nSeq NUMBER;
v_sql long;
begin
v_sql:='select '||upper(spSeq)||'.nextval from dual';
execute immediate v_sql into nSeq;
return nSeq;
end;
/
There are some limitations on how NEXTVAL can be used. There's a list in the Oracle docs. More to the point, the link includes a list of conditions where NEXTVAL will be called more than once.
The only scenario named on the page where a straight SELECT will call NEXTVAL more than once is in "A top-level SELECT statement". A crude query that will call NEXTVAL twice is:
SELECT seq.NEXTVAL FROM (
SELECT * FROM DUAL
CONNECT BY LEVEL <= 2) -- Change the "2" to get more sequences
Unfortunately, if you try to push this into a subquery to flatten out the values to one row with columns v1 and v2 (like in your question), you'll get the ORA-02287: sequence number not allowed here.
This is as close as I could get. If the query above won't help you get where you want, then check out the other answers that have been posted here. As I've been typing this, a couple of excellent answers have been posted.
Telling you to just call sequence.nextval multiple times would be boring, so here's what you can try:
create type t_num_tab as table of number;
CREATE SEQUENCE SEQ_TEST
START WITH 1
MAXVALUE 999999999999999999999999999
MINVALUE 1
NOCYCLE
CACHE 100
NOORDER;
create or replace function get_seq_vals(i_num in number) return t_num_tab is
seq_tab t_num_tab;
begin
select SEQ_TEST.nextval
bulk collect into seq_tab
from all_objects
where rownum <= i_num;
return seq_tab;
end;
And you can use it as follows. This example is pulling 7 numbers at once from the sequence:
declare
numbers t_num_tab;
idx number;
begin
-- this grabs x numbers at a time
numbers := get_seq_vals(7);
-- this just loops through the returned numbers
-- to show the values
idx := numbers.first;
loop
dbms_output.put_line(numbers(idx));
idx := numbers.next(idx);
exit when idx is null;
end loop;
end;
Also note that I use "next" instead of first..last as its possible you may want to remove numbers from the list before iterating through (or, sometimes a sequence cache can results in numbers incrementing by more than 1).
These are all great answers, unfortunately it was just not enough. Will definitely be able to return to this page when struggling in the future.
I have gone with a different method. Asked a new question and got my answer.
You can go check it out here.