In PostgreSQL 8.4.9 I have a small game, where users can purchase a VIP ("very important person") status:
# \d pref_users;
Table "public.pref_users"
Column | Type | Modifiers
------------+-----------------------------+---------------
id | character varying(32) | not null
vip | timestamp without time zone |
If vip has never been purchased it will be NULL.
If vip has expired it will be < CURRENT_TIMESTAMP.
I'm trying to create PL/pgSQL procedure allowing users with enough vip status left to give a week of it to other users, as a "gift":
create or replace function pref_move_week(_from varchar,
_to varchar) returns void as $BODY$
declare
has_vip boolean;
begin
select vip > current_timestamp + interval '1 week'
into has_vip from pref_users where id=_from;
if (not has_vip) then
return;
end if;
update pref_users set vip = current_timestamp - interval '1 week' where id=_from;
update pref_users set vip = current_timestamp + interval '1 week' where id=_to;
end;
$BODY$ language plpgsql;
Unfortunately this procedure does not work properly if vip of the giving user is NULL:
# update pref_users set vip=null where id='DE16290';
UPDATE 1
# select id,vip from pref_users where id in ('DE16290', 'DE1');
id | vip
---------+----------------------------
DE1 | 2012-01-05 17:35:17.772043
DE16290 |
(2 rows)
# select pref_move_week('DE16290', 'DE1');
pref_move_week
----------------
(1 row)
# select id,vip from pref_users where id in ('DE16290', 'DE1');
id | vip
---------+----------------------------
DE1 | 2012-01-05 17:43:11.589922
DE16290 | 2011-12-22 17:43:11.589922
(2 rows)
I.e. the IF-statement above doesn't seem to work and falls through.
Also I wonder if the has_vip variable is needed here at all?
And how could I ensure that the primary keys _from and _to are really present in the pref_users table or is this already taken care of (because one of the UPDATE statements will "throw an exception" and the transaction will be rollbacked)?
UPDATE:
Thank you for all the replies and I've also got a tip to use:
if (not coalesce(has_vip, false)) then
return;
end if;
But now I have a new problem:
# select id,vip from pref_users where id in ('DE16290', 'DE1');
id | vip
---------+----------------------------
DE1 | 2012-01-05 17:43:11.589922
DE16290 |
(2 rows)
(i.e. DE1 has vip until May and should be able to give a week to DE16290, but):
# select pref_move_week('DE1', 'DE16290');
pref_move_week
----------------
(1 row)
# select id,vip from pref_users where id in ('DE16290', 'DE1');
id | vip
---------+----------------------------
DE1 | 2012-01-05 17:43:11.589922
DE16290 |
(2 rows)
(For some reason nothing has changed?)
UPDATE 2: The final solution -
create or replace function pref_move_week(_from varchar,
_to varchar) returns void as $BODY$
begin
select 1 from pref_users
where id=_from and
vip > current_timestamp + interval '1 week';
if not found then
return;
end if;
update pref_users set
vip = vip - interval '1 week'
where id=_from;
update pref_users set
vip = greatest(vip, current_timestamp) + interval '1 week'
where id=_to;
end;
$BODY$ language plpgsql;
When comparing your timestamp to something that might be null, you can use the COALESE function to supply a "default" value to compare against. For example,
select 1 from pref_users
where id=_from and
vip > COALESCE(current_timestamp, to_timestamp(0));
The COALESCE function returns the first non-null from its list. See docs. (Also to_timestamp() docs...)
Null values return false on any compare short of is null (so where null <> 1 is false and null = 1 is false...null never equals or not equals anything). Instead of
if (not has_vip) then return
go with
if (not has_vip) or has_vip is null then return
The syntax you are using is a bit unique here and I'm not used to reading it...guessing you've come from a different background than SQL and haven't encountered null fun yet. Null is a special concept in SQL that you'll need to handle differently. Remember it is not equal to blank or 0, nor is it less than or greater than any number.
Edit in:
I'm a bit confused by this:
select vip > current_timestamp + interval '1 week'
into has_vip from pref_users where id=_from;
I believe this is equivalent to:
select vip
into has_vip from pref_users
where id=_from
and vip > current_timestamp + interval '1 week';
I hope anyway. Now this is going to return a null if no record is found or if the VIP value is null. can you just go if has_vip is null then return?
There may be a more elegant solution but I think
SELECT (vip IS NOT NULL) AND (vip > current_timestamp + interval '1 week')
would do the work.
I guess your problem is related to the fact that NULL is neither true or false.
You may find more info in the docs.
Related
Is there a better way of doing this?
Basically, I have a users table, and on of the columns is birth_date (date)
I am supposed to filter by age range, meaning, I will get a range like 18-24.
This will be passed to a function in a jsonb parameter, as an array of 2 integers.
So I have done the following
create or replace function my_filter_function(
p_search_parameters jsonb
)
returns TABLE(
user_id bigint,
birth_date date,
age interval,
years double precision
)
security definer
language plpgsql
as
$$
begin
return query
select u.user_id, u.birth_date, age(u.birth_date), date_part('year', age(u.birth_date))
from users u
where u.birth_date is not null
and ( (p_search_parameters#>>'{age,0}') is null or u.birth_date <= (now() - ((p_search_parameters#>>'{age,0}')::integer * interval '1 year'))::date)
and ( (p_search_parameters#>>'{age,1}') is null or u.birth_date >= (now() - ((p_search_parameters#>>'{age,1}')::integer * interval '1 year'))::date)
;
end;
$$;
-- this is just a aluttle helpder function to better post and explain the question
This seems to be doing the job, but was hoping to find other ways of doing this while still getting a jsonb parameter, array of 2 integers
Any ideas?
I have a set of records in a table, with some records having invalid date. I wanted to ignore those invalid records and do a check with rest of the records. I framed a query like below but I don't find it working.
select * from tbl_name i
where is_date(i.dob) and i.dob::date > CURRENT_DATE;
I got to know that sql doesn't short circuit so it also consider invalid record and end up in date/time out of range. Please help me alter this query in a way i could eliminate invalid dates and do date comparison on valid dates only.
There is no guarantee for short-circuiting in Postgres. Neither in a "plain" WHERE clause, nor when using a derived table (from (select ...) where ...). One way to force the evaluation in two steps would be a materialized common table expressions:
with data as materialized (
select *
from tbl_name i
where is_date(i.dob)
)
select *
from data
where dob::date > CURRENT_DATE;
The materialized keyword prevents the optimizer from pushing the condition of the outer query into the CTE.
Obviously this assumes that is_date() will never return false positives
Using CASE in the WHERE to differentiate between a valid date and an invalid one and run the > comparison for valid date otherwise return FALSE.
create or replace function is_date(s varchar) returns boolean as $$
begin
if s is null then
return false;
end if;
perform s::date;
return true;
exception when others then
return false;
end;
$$ language plpgsql;
create table date_str (id integer, dt_str varchar);
insert into date_str values (1, '2022-11-02'), (2, '1234'), (3, '2022-12-03');
insert into date_str values (4, 'xyz'), (5, '2022-01-01'), (6, '2023-02-02');
select * from date_str;
id | dt_str
----+------------
1 | 2022-11-02
2 | 1234
3 | 2022-12-03
4 | xyz
5 | 2022-01-01
6 | 2023-02-02
select current_date;
current_date
--------------
11/02/2022
SELECT
*
FROM
date_str
WHERE
CASE WHEN is_date (dt_str) = 't' THEN
dt_str::date > CURRENT_DATE
ELSE
FALSE
END;
id | dt_str
----+------------
3 | 2022-12-03
6 | 2023-02-02
Online poker players can optionally purchase access to playroom 1 or playroom 2.
And they can be temporarily banned for cheating.
CREATE TABLE users (
uid SERIAL PRIMARY KEY,
paid1_until timestamptz NULL, -- may play in room 1
paid2_until timestamptz NULL, -- may play in room 2
banned_until timestamptz NULL, -- punished for cheating etc.
banned_reason varchar(255) NULL
);
Here the above table is filled with 4 test records:
INSERT INTO users (paid1_until, paid2_until, banned_until, banned_reason)
VALUES (NULL, NULL, NULL, NULL),
(current_timestamp + interval '1 month', NULL, NULL, NULL),
(current_timestamp + interval '2 month', current_timestamp + interval '4 month', NULL, NULL),
(NULL, current_timestamp + interval '8 month', NULL, NULL);
All 4 records belong to the same person - who has authenticated herself via different social networks (for example through Facebook, Twitter, Apple Game Center, etc.)
I am trying to create a stored function, which would take a list of numeric user ids (as a JSON array) and merge records belonging to same person into a single record - without losing her payments or punishments:
CREATE OR REPLACE FUNCTION merge_users(
IN in_users jsonb,
OUT out_uid integer)
RETURNS integer AS
$func$
DECLARE
new_paid1 timestamptz;
new_paid2 timestamptz;
new_banned timestamptz;
new_reason varchar(255);
BEGIN
SELECT min(uid),
current_timestamp + sum(paid1_until - current_timestamp),
current_timestamp + sum(paid2_until - current_timestamp),
max(banned_until)
INTO
out_uid, new_paid1, new_paid2, new_banned
FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users));
IF out_uid IS NOT NULL THEN
SELECT banned_reason
INTO new_reason
FROM users
WHERE new_banned IS NOT NULL
AND banned_until = new_banned
LIMIT 1;
DELETE FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
AND uid <> out_uid;
UPDATE users
SET paid1_until = new_paid1,
paid2_until = new_paid2,
banned_until = new_banned,
banned_reason = new_reason
WHERE uid = out_uid;
END IF;
END
$func$ LANGUAGE plpgsql;
Unfortunately, its usage results in the following error:
# TABLE users;
uid | paid1_until | paid2_until | banned_until | banned_reason
-----+-------------------------------+-------------------------------+--------------+---------------
1 | | | |
2 | 2016-03-27 19:47:55.876272+02 | | |
3 | 2016-04-27 19:47:55.876272+02 | 2016-06-27 19:47:55.876272+02 | |
4 | | 2016-10-27 19:47:55.876272+02 | |
(4 rows)
# select merge_users('[1,2,3,4]'::jsonb);
ERROR: operator does not exist: integer = jsonb
LINE 6: WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
QUERY: SELECT min(uid),
current_timestamp + sum(paid1_until - current_timestamp),
current_timestamp + sum(paid2_until - current_timestamp),
max(banned_until)
FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
CONTEXT: PL/pgSQL function merge_users(jsonb) line 8 at SQL statement
Please help me to solve the problem.
Here is a gist with SQL code for your convenience.
Result of jsonb_array_elements() is a set of jsonb elements, therefore you need add explicit cast of uid to jsonb with to_jsonb() function, IN will be replaced with <# operator:
WITH t(val) AS ( VALUES
('[1,2,3,4]'::JSONB)
)
SELECT TRUE
FROM t,jsonb_array_elements(t.val) element
WHERE to_jsonb(1) <# element;
For your case, snippet should be adjusted to something like:
...SELECT ...,JSONB_ARRAY_ELEMENTS(in_users) user_ids
WHERE to_jsonb(uid) <# user_ids...
In PostgreSQL 9.3 I have the following table with 2 timestamps:
create table pref_users (
id varchar(32) primary key,
first_name varchar(64) not null,
last_name varchar(64),
female boolean,
avatar varchar(128),
city varchar(64),
mobile varchar(64),
login timestamp default current_timestamp,
logout timestamp,
last_ip inet,
vip timestamp, /* XXX can be NULL */
grand timestamp, /* XXX can be NULL */
mail varchar(256),
green integer,
red integer,
medals integer not null default 0
);
The timestamps vip and grand indicate if the users of my game have paid for certain privilleges - until those dates.
When a user connects to my game server, I call the following procedure with OUT parameters:
create or replace function pref_get_user_info(
IN _id varchar,
OUT is_banned boolean,
OUT is_grand boolean,
OUT is_vip boolean,
OUT rep integer
) as $BODY$
begin
is_banned := exists(select 1 from pref_ban where id=_id);
if is_banned then
return;
end if;
select
grand > current_timestamp,
vip > current_timestamp,
into is_grand is_vip
from pref_users where id=_id;
if is_grand or is_vip then
return;
end if;
select
count(nullif(nice, false)) -
count(nullif(nice, true))
into rep
from pref_rep where id=_id;
end;
$BODY$ language plpgsql;
This does work well, but sometimes delivers NULL values to my game daemon (to a Perl script):
# select * from pref_get_user_info('OK674418426646');
is_banned | is_grand | is_vip | rep
-----------+----------+--------+-----
f | | | 126
(1 row)
I don't need a NULL though (and it prints a warning in my Perl script) - I just need a "true" or "false" values there.
So I have tried:
select
coalesce(grand, 0) > current_timestamp,
coalesce(vip, 0) > current_timestamp,
into is_grand is_vip
from pref_users where id=_id;
But this gives me error:
# select * from pref_get_user_info('OK674418426646');
ERROR: COALESCE types timestamp without time zone and integer cannot be matched
LINE 2: coalesce(grand, 0) > current_timesta...
^
QUERY: select
coalesce(grand, 0) > current_timestamp,
coalesce(vip, 0) > current_timestamp,
is_vip
from pref_users where id=_id
CONTEXT: PL/pgSQL function pref_get_user_info(character varying) line 9 at SQL statement
So I wonder what to do here please?
Do I really have to
select
coalesce(grand, current_timestamp - interval '1 day') > current_timestamp,
coalesce(vip, current_timestamp - interval '1 day') > current_timestamp,
into is_grand is_vip
from pref_users where id=_id;
or is there maybe a nicer way (like maybe "epoch start" or "yesterday")?
UPDATE:
As suggested by Clodoaldo Neto (thanks!) I've tried:
select
coalesce(grand > current_timestamp, false),
coalesce(vip > current_timestamp, false),
into is_grand is_vip
from pref_users where id=_id;
but is_vip is NULL when vip is NULL:
# select * from pref_get_user_info('OK674418426646');
is_banned | is_grand | is_vip | rep
-----------+----------+--------+-----
f | t | |
(1 row)
And when I try either of the following I get syntax error:
select
coalesce(grand > current_timestamp, false),
coalesce(vip > current_timestamp, false),
into is_grand, is_vip
from pref_users where id=_id;
select
coalesce(grand > current_timestamp, false),
coalesce(vip > current_timestamp, false),
into (is_grand, is_vip)
from pref_users where id=_id;
How can I SELECT into 2 variables at once here?
If you want a boolean:
coalesce(grand > current_timestamp, false)
If you need 0 or 1:
coalesce((grand > current_timestamp)::integer, 0)
In your updated question you have an extra comma between the select list and the into clause
coalesce(vip > current_timestamp, false),
into is_grand, is_vip
Take it out
coalesce(vip > current_timestamp, false)
into is_grand, is_vip
One of our Postgres tables, called rep_event, has a timestamp column that indicates when each row was inserted. But all of the rows have a timestamp value of 2000-01-01 00:00:00, so something isn't set up right.
There is a function that inserts rows into the table, and it is the only code that inserts rows into that table - no other code inserts into that table. (There also isn't any code that updates the rows in that table.) Here is the definition of the function:
CREATE FUNCTION handle_event() RETURNS "trigger"
AS $$
BEGIN
IF (TG_OP = 'DELETE') THEN
INSERT INTO rep_event SELECT 'D', TG_RELNAME, OLD.object_id, now();
RETURN OLD;
ELSIF (TG_OP = 'UPDATE') THEN
INSERT INTO rep_event SELECT 'U', TG_RELNAME, NEW.object_id, now();
RETURN NEW;
ELSIF (TG_OP = 'INSERT') THEN
INSERT INTO rep_event SELECT 'I', TG_RELNAME, NEW.object_id, now();
RETURN NEW;
END IF;
RETURN NULL;
END;
$$ LANGUAGE plpgsql;
Here is the table definition:
CREATE TABLE rep_event
(
operation character(1) NOT NULL,
table_name text NOT NULL,
object_id bigint NOT NULL,
time_stamp timestamp without time zone NOT NULL
)
As you can see, the now() function is called to get the current time. Doing a "select now()" on the database returns the correct time, so is there an issue with calling now() from within a function?
A simpler solution is to just modify your table definition to have NOW() be the default value:
CREATE TABLE rep_event (
operation character(1) NOT NULL,
table_name text NOT NULL,
object_id bigint NOT NULL,
time_stamp timestamp without time zone NOT NULL DEFAULT NOW()
);
Then you can get rid of the now() calls in your trigger.
Also as a side note, I strongly suggest including the column ordering in your function... IOW;
INSERT INTO rep_event (operation,table_name,object_id,time_stamp) SELECT ...
This way if you ever add a new column or make other table changes that change the internal ordering of the tables, your function won't suddenly break.
Your problem has to be elsewhere, as your function works well. Create test database, paste the code you cited and run:
create table events (object_id bigserial, data text);
create trigger rep_event
before insert or update or delete on events
for each row execute procedure handle_event();
insert into events (data) values ('v1'),('v2'),('v3');
delete from events where data='v2';
update events set data='v4' where data='v3';
select * from events;
object_id | data
-----------+------
1 | v1
3 | v4
select * from rep_event;
operation | table_name | object_id | time_stamp
-----------+------------+-----------+----------------------------
I | events | 1 | 2011-07-08 10:31:50.489947
I | events | 2 | 2011-07-08 10:31:50.489947
I | events | 3 | 2011-07-08 10:31:50.489947
D | events | 2 | 2011-07-08 10:32:12.65699
U | events | 3 | 2011-07-08 10:32:33.662936
(5 rows)
Check other triggers, trigger creation command etc. And change this timestamp without timezone to timestamp with timezone.