I would like to store a table variable as to be accessed by another query within a function. Here is what I have so far.
CREATE OR REPLACE FUNCTION suggest(p_id INTEGER)
RETURNS TABLE (
r_id INT,
i_id INT
) AS $$
DECLARE
p_record INT[];
BEGIN
SELECT ingredient_id INTO p_record FROM shop_ingredients
WHERE item_id IN
(SELECT item_id FROM basket
WHERE user_id = p_id);
...
I am not sure whether the type of p-record should be an array of INTEGER or a RECORD. Within the function I would like to access such list of values, for example:
HAVING SUM(ingredient_id = ANY(p_record)) >= (COUNT(*)*0.6)
How can I achieve this? I have searched endlessly to understand how to manage this but to no avail.
The problem with creating a table, like so:
CREATE TEMP TABLE IF NOT EXISTS p_record
AS SELECT ingredient_id
FROM shop_ingredients
WHERE item_id IN
(SELECT item_id FROM basket
WHERE user_id = p_id);
is that if p_id parameter changes, the p_record variables does not.
Maybe the following SQL function can help:
create or replace function suggest(p_id int)
returns table (i_id int)
language sql
as
$$
select ingredient_id
from shop_ingredient
where item_id in
(select item_id from basket
where user_id = p_id);
$$;
Note that the SELECT statement column list must exactly match the TABLE clause after RETURNS keyword and this function is only SQL so no need of BEGIN/END block or intermediate record variable.
Related
Steps for Execution:
Table Creation
CREATE TABLE xyz.table_a(
id bigint NOT NULL,
scores jsonb,
CONSTRAINT table_a_pkey PRIMARY KEY (id)
);
Add some dummy data :
INSERT INTO xyz.table_a(
id, scores)
VALUES (1, '{"a":20,"b":20}');
Function Creation
CREATE OR REPLACE FUNCTION xyz.example(
table_name text,
regular_columns text,
json_column text,
view_name text
) RETURNS text
LANGUAGE 'plpgsql'
COST 100
VOLATILE
AS $BODY$
DECLARE
cols TEXT;
cols_sum TEXT;
BEGIN
EXECUTE
format(
$ex$SELECT string_agg(
format(
'CAST(%2$s->>%%1$L AS INTEGER)',
key),
', '
)
FROM (SELECT DISTINCT key
FROM %1$s, jsonb_each(%2$s)
ORDER BY 1
) s;$ex$,
table_name, json_column
)
INTO cols;
EXECUTE
format(
$ex$SELECT string_agg(
format(
'CAST(%2$s->>%%1$L AS INTEGER)',
key
),
'+'
)
FROM (SELECT DISTINCT key
FROM %1$s, jsonb_each(%2$s)
ORDER BY 1) s;$ex$,
table_name, json_column
)
INTO cols_sum;
EXECUTE
format(
$ex$DROP VIEW IF EXISTS %2$s;
CREATE VIEW %2$s AS
SELECT %3$s, %4$s, SUM(%5$s) AS total
FROM %1$s
GROUP BY %3$s$ex$,
table_name, view_name, regular_columns, cols, cols_sum
);
RETURN cols;
END
$BODY$:
Call Function
SELECT xyz.example(
'xyz.table_a',
' id',
'scores',
'xyz.view_table_a'
);
Once you run these steps, I am getting an error
ERROR: column "int4" specified more than once
CONTEXT: SQL statement "
DROP VIEW IF EXISTS xyz.view_table_a;
CREATE VIEW xyz.view_table_a AS
SELECT id, CAST(scores->>'a' AS INTEGER), CAST(scores->>'b' AS INTEGER), SUM(CAST(scores->>'a' AS INTEGER)+CAST(scores->>'b' AS INTEGER)) AS total FROM xyz.table_a GROUP BY id
Look at the error message closely:
...
SELECT id, CAST(scores->>'a' AS INTEGER), CAST(scores->>'b' AS INTEGER),
...
There are multiple expressions without column alias. A named column like "id" defaults to the given name. But other expressions default to the internal type name, which is "int4" for integer. One might assume that the JSON key name is used, but that's not so. CAST(scores->>'a' AS INTEGER) is just another expression returning an unnamed integer value.
This still works for a plain SELECT. Postgres tolerates duplicate column names in the (outer) SELECT list. But a VIEW cannot be created that way. Would result in ambiguities.
Either add column aliases to expressions in the SELECT list:
SELECT id, CAST(scores->>'a' AS INTEGER) AS a, CAST(scores->>'b' AS INTEGER) AS b, ...
Or add a list of column names to CREATE VIEW:
CREATE VIEW xyz.view_table_a(id, a, b, ...) AS ...
Something like this should fix your function (preserving literal spelling of JSON key names:
...
format(
'CAST(%2$s->>%%1$L AS INTEGER) AS %%1$I',
key),
...
See the working demo here:
db<>fiddle here
Aside, your nested format() calls make the code pretty hard to read and maintain.
I have a summary table that is updated with new data on a regulary basis. One of the columns is of type hstore. When I update with new data I want to add the value of a key to the existing value of the key if the key exists, otherwise I want to add the pair to the hstore.
Existing data:
id sum keyvalue
--------------------------------------
1 2 "key1"=>"1","key2"=>"1"
New data:
id sum keyvalue
--------------------------------------------------
1 3 "key1"=>"1","key2"=>"1","key3"=>"1"
Wanted result:
id sum keyvalue
--------------------------------------------------
1 5 "key1"=>"2","key2"=>"2","key3"=>"1"
I want to do this in a on conflict part of an insert.
The sum part was easy. But I have not found how to concatenate the hstore in this way.
There is nothing built int. You have to write a function that accepts to hstore values and merges them in the way you want.
create function merge_and_increment(p_one hstore, p_two hstore)
returns hstore
as
$$
select hstore_agg(hstore(k,v))
from (
select k, sum(v::int)::text as v
from (
select *
from each(p_one) as t1(k,v)
union all
select *
from each(p_two) as t2(k,v)
) x
group by k
) s
$$
language sql;
The hstore_agg() function isn't built-in as well, but it's easy to define it:
create aggregate hstore_agg(hstore)
(
sfunc = hs_concat(hstore, hstore),
stype = hstore
);
So the result of this:
select merge_and_increment(hstore('"key1"=>"1","key2"=>"1"'), hstore('"key1"=>"1","key2"=>"1","key3"=>"1"'))
is:
merge_and_increment
-------------------------------------
"key1"=>"2", "key2"=>"2", "key3"=>"1"
Note that the function will fail miserably if there are values that can't be converted to an integer.
With an insert statement you can use it like this:
insert into the_table (id, sum, data)
values (....)
on conflict (id) do update
set sum = the_table.sum + excluded.sum,
data = merge_and_increment(the_table.data, excluded.data);
demo:db<>fiddle
CREATE OR REPLACE FUNCTION sum_hstore(_old hstore, _new hstore) RETURNS hstore
AS $$
DECLARE
_out hstore;
BEGIN
SELECT
hstore(array_agg(key), array_agg(value::text))
FROM (
SELECT
key,
SUM(value::int) AS value
FROM (
SELECT * FROM each('"key1"=>"1","key2"=>"1"'::hstore)
UNION ALL
SELECT * FROM each('"key1"=>"1","key2"=>"1","key3"=>"1"')
) s
GROUP BY key
) s
INTO _out;
RETURN _out;
END;
$$
LANGUAGE plpgsql;
each() expands the key/value pairs into one row per pair with columns key and value
convert type text into type int and group/sum the values
Aggregate into a new hstore value using the hstore(array, array) function. The array elements are the values of the key column and the values of the value column.
You can do such an update:
UPDATE mytable
SET keyvalue = sum_hstore(keyvalue, '"key1"=>"1","key2"=>"1","key3"=>"1"')
WHERE id = 1;
I have a select query that returns a dataset with "n" records in one column. I would like to use this column as the parameter in a stored procedure. Below a reduced example of my case.
The query:
SELECT code FROM rawproducts
The dataset:
CODE
1
2
3
The stored procedure:
ALTER PROCEDURE [dbo].[MyInsertSP]
(#code INT)
AS
BEGIN
INSERT INTO PRODUCTS description, price, stock
SELECT description, price, stock
FROM INVENTORY I
WHERE I.icode = #code
END
I already have the actual query and stored procedure done; I just am not sure how to put them both together.
I would appreciate any assistance here! Thank you!
PS: of course the stored procedure is not as simple as above. I just choose to use a very silly example to keep things small here. :)
Here's two methods for you, one using a loop without a cursor:
DECLARE #code_list TABLE (code INT);
INSERT INTO #code_list SELECT code, ROW_NUMBER() OVER (ORDER BY code) AS row_id FROM rawproducts;
DECLARE #count INT;
SELECT #count = COUNT(*) FROM #code_list;
WHILE #count > 0
BEGIN
DECLARE #code INT;
SELECT #code = code FROM #code_list WHERE row_id = #count;
EXEC MyInsertSP #code;
DELETE FROM #code_list WHERE row_id = #count;
SELECT #count = COUNT(*) FROM #code_list;
END;
This works by putting the codes into a table variable, and assigning a number from 1..n to each row. Then we loop through them, one at a time, deleting them as they are processed, until there is nothing left in the table variable.
But here's what I would consider a better method:
CREATE TYPE dbo.code_list AS TABLE (code INT);
GO
CREATE PROCEDURE MyInsertSP (
#code_list dbo.code_list)
AS
BEGIN
INSERT INTO PRODUCTS (
[description],
price,
stock)
SELECT
i.[description],
i.price,
i.stock
FROM
INVENTORY i
INNER JOIN #code_list cl ON cl.code = i.code;
END;
GO
DECLARE #code_list dbo.code_list;
INSERT INTO #code_list SELECT code FROM rawproducts;
EXEC MyInsertSP #code_list = #code_list;
To get this to work I create a user-defined table type, then use this to pass a list of codes into the stored procedure. It means slightly rewriting your stored procedure, but the actual code to do the work is much smaller.
(how to) Run a stored procedure using select columns as input
parameters?
What you are looking for is APPLY; APPLY is how you use columns as input parameters. The only thing unclear is how/where the input column is populated. Let's start with sample data:
IF OBJECT_ID('dbo.Products', 'U') IS NOT NULL DROP TABLE dbo.Products;
IF OBJECT_ID('dbo.Inventory','U') IS NOT NULL DROP TABLE dbo.Inventory;
IF OBJECT_ID('dbo.Code','U') IS NOT NULL DROP TABLE dbo.Code;
CREATE TABLE dbo.Products
(
[description] VARCHAR(1000) NULL,
price DECIMAL(10,2) NOT NULL,
stock INT NOT NULL
);
CREATE TABLE dbo.Inventory
(
icode INT NOT NULL,
[description] VARCHAR(1000) NULL,
price DECIMAL(10,2) NOT NULL,
stock INT NOT NULL
);
CREATE TABLE dbo.Code(icode INT NOT NULL);
INSERT dbo.Inventory
VALUES (10,'',20.10,3),(11,'',40.10,3),(11,'',25.23,3),(11,'',55.23,3),(12,'',50.23,3),
(15,'',33.10,3),(15,'',19.16,5),(18,'',75.00,3),(21,'',88.00,3),(21,'',100.99,3);
CREATE CLUSTERED INDEX uq_inventory ON dbo.Inventory(icode);
The function:
CREATE FUNCTION dbo.fnInventory(#code INT)
RETURNS TABLE AS RETURN
SELECT i.[description], i.price, i.stock
FROM dbo.Inventory I
WHERE I.icode = #code;
USE:
DECLARE #code TABLE (icode INT);
INSERT #code VALUES (10),(11);
SELECT f.[description], f.price, f.stock
FROM #code AS c
CROSS APPLY dbo.fnInventory(c.icode) AS f;
Results:
description price stock
-------------- -------- -----------
20.10 3
40.10 3
Updated Proc (note my comments):
ALTER PROC dbo.MyInsertSP -- (1) Lose the input param
AS
-- (2) Code that populates the "code" table
INSERT dbo.Code VALUES (10),(11);
-- (3) Use CROSS APPLY to pass the values from dbo.code to your function
INSERT dbo.Products ([description], price, stock)
SELECT f.[description], f.price, f.stock
FROM dbo.code AS c
CROSS APPLY dbo.fnInventory(c.icode) AS f;
This ^^^ is how it's done.
The end result of what I am after is a query that calls a function and that function returns a set of records that are in their own separate fields. I can do this but the results of the function are all in one field.
ie: http://i.stack.imgur.com/ETLCL.png and the results I am after are: http://i.stack.imgur.com/wqRQ9.png
Here's the code to create the table
CREATE TABLE tbl_1_hm
(
tbl_1_hm_id bigserial NOT NULL,
tbl_1_hm_f1 VARCHAR (250),
tbl_1_hm_f2 INTEGER,
CONSTRAINT tbl_1_hm PRIMARY KEY (tbl_1_hm_id)
)
-- do that for a few times to get some data
INSERT INTO tbl_1_hm (tbl_1_hm_f1, tbl_1_hm_f2)
VALUES ('hello', 1);
CREATE OR REPLACE FUNCTION proc_1_hm(id BIGINT)
RETURNS TABLE(tbl_1_hm_f1 VARCHAR (250), tbl_1_hm_f2 int AS $$
SELECT tbl_1_hm_f1, tbl_1_hm_f2
FROM tbl_1_hm
WHERE tbl_1_hm_id = id
$$ LANGUAGE SQL;
--And here is the current query I am running for my results:
SELECT t1.tbl_1_hm_id, proc_1_hm(t1.tbl_1_hm_id) AS t3
FROM tbl_1_hm AS t1
Thanks for having a read. Please if you want to haggle about the semantics of what I am doing by hitting the same table twice or my naming convention --> this is a simplified test.
When a function returns a set of records, you should treat it as a table source:
SELECT t1.tbl_1_hm_id, t3.*
FROM tbl_1_hm AS t1, proc_1_hm(t1.tbl_1_hm_id) AS t3;
Note that functions are implicitly using a LATERAL join (scroll down to sub-sections 4 and 5) so you can use fields from tables listed previously without having to specify an explicit JOIN condition.
Say I have a table, created as follows:
CREATE TABLE test_table (id serial, unique_id varchar(50) primary key, name varchar(50));
test_table
----------
id | unique_id | name
In that table, I would like to update the unique_id field with the newly inserted id concatenated with the inserted name in a single go.
Usually this is accomplished by two queries. (PHP way)
$q = "INSERT INTO table (unique_id,name) values ('uid','abc') returning id||name as unique_id;";
$r = pg_query($dbconn,$q);
$row = pg_fetch_array($r);
$q1 = "UPDATE test_table set unique_id =".$row['unique_id']." where unique_id='uid'";
$r1 = pg_query($dbconn,$q1);
Is there any way to do the above in a single query?
You can have several options here, you could create a AFTER trigger which uses the generated ID for an direct update of the same row:
CREATE TRIGGER test_table_insert ON AFTER INSERT ON test_table FOR EACH ROW EXECUTE PROCEDURE test_table_insert();
And in your function you update the value:
CREATE FUNCTION test_table_insert() RETURNS TRIGGER AS $$
BEGIN
UPDATE test_table SET uniqid = NEW.id::text || NEW.name WHERE id = NEW.id;
END;
$$ LANGUAGE plpgsql;
You need to add the function before the trigger.
An other option would be to do it directly in the insert:
INSERT INTO table (id, unique_id, name) values (nextval('test_table_id_seq'), 'abc', currval('test_table_id_seq')::text || 'abc') returning id;
But as a_horse_with_no_name pointed out, I think you may have a problem in your database design.