I have been working on creating a store procedure that will select data from a table, do some modification to that data, and then I need to insert that modified data into the same table. Take an example my table name is student. My procedure looks like below:
create or replace procedure student_create(p_code varchar)
language plpgsql
as $$
declare
v_student public.student;
begin
select * into v_student from student where code = p_code and is_latest_version is true;
raise notice 'Value: %', v_student;
v_student.id = uuid_generate_v4();
v_student.version_created_at = now();
v_student.version_updated_at = v_student.version_created_at;
raise notice 'Value: %', v_student;
INSERT INTO public.student VALUES(v_student);
end;$$
I am getting errors while calling this procedure:
ERROR: column "id" is of type uuid but expression is of type hotel
LINE 1: INSERT INTO public.hotel VALUES(v_hotel)
I know I can make insert statements like I can get each value from the variable and set it like
INSERT INTO public.student VALUES(v_student.id, v_student.code, v_student.name);
But I don't want to do that because it will become tightly coupled and later if I add another column into the table then I need to add that column into this procedure as well.
Does anyone have idea how can I insert the declared type variable directly into table.
There is no table type, there is only row composite type. Check manual 43.3.4. Row Types.
use row type.
create or replace procedure student_create(p_code text)
language plpgsql
as $$
declare
v_student public.student
begin
for v_student in select * from student where code = p_code and is_latest_version is true
loop
v_student.id = uuid_generate_v4();
v_student.version_created_at = now();
v_student.version_updated_at = v_student.version_created_at;
v_student.is_latest_version = true;
v_student.code = p_code;
INSERT INTO student VALUES(v_student.*);
end loop;
end;$$;
call it: call student_create('hello');
3. use update clause directly.
create or replace procedure student_create_1(p_code text)
language plpgsql as $$
BEGIN
with a as ( select uuid_generate_v4() as id ,
now() as version_created_at,
now() as version_updated_at,
p_code as "code" from student
where code = p_code and is_latest_version is true)
INSERT INTO student(id, version_created_at, version_updated_at, code)
select a.id, a.version_created_at,a.version_updated_at,a."code" from a;
end
$$;
call it: call student_create_1('hello');
fiddle code: here
Related
I have 30 state wise data tables. Table name like aa_shg_detail, ab_shg_detail, ac_shg_detail.
I have also main state table in which state short names and state codes are stored. I have created 2 postgresql functions getTableName(Code text) and getDataByTable().
In the first function I pass the state code so it fetches the state short name and short name concat with _shg_detail String and prepare full table name and return it. Example: If I pass state code 2 the query fetch state short name based on state code 2 from the state's main table. The state short name is 'ab' for state code 2 so after concat state short name with _shg_detail first function return ab_shg_detail table name.
Second function gets the table name from first function and fetch data from that table. But I am getting error in the second function.
CREATE OR REPLACE FUNCTION getTableName(code text)
RETURNS text
AS $$
select concat(lower(state_short_name), '_shg_detail') from main_state where state_code = code))
$$
LANGUAGE sql;
CREATE OR REPLACE FUNCTION getDataByTable()
RETURNS text AS $$
DECLARE
tablename text;
BEGIN
tablename := gettablename('2');
RETURN (select shg_code from tablename);
END;
$$ LANGUAGE plpgsql;
When I execute a second function select getDataByTable() then I am getting this error every time:
ERROR: relation "tablename" does not exist
LINE 1: SELECT (select shg_code from tableName)
You need dynamic SQL for that:
CREATE OR REPLACE FUNCTION getDataByTable()
RETURNS text AS $$
DECLARE
tablename text;
l_result text;
BEGIN
tablename := gettablename('2');
execute format('select shg_code from %I', tablename)
into l_result;
RETURN l_result;
END;
$$ LANGUAGE plpgsql;
The %I placeholder of the format() function properly deals with quoting of identifiers if needed.
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 have a dynamic variable that I can specify different column's with (depending on some if statements). Explained in code, I am trying to replace this:
IF (TG_TABLE_NAME='this') THEN INSERT INTO table1 (name_id) VALUES id.NEW END IF;
IF (TG_TABLE_NAME='that') THEN INSERT INTO table1 (lastname_id) VALUES id.NEW END IF;
IF (TG_TABLE_NAME='another') THEN INSERT INTO table1 (age_id) VALUES id.NEW END IF;
With this:
DECLARE
varName COLUMN;
BEGIN
IF (TG_TABLE_NAME='this') THEN varName = 'name_id';
ELSE IF (TG_TABLE_NAME='that') THEN varName = 'lastname_id';
ELSE (TG_TABLE_NAME='another') THEN varName = 'age_id';
END IF;
INSERT INTO table1 (varName) VALUES id.NEW;
END;
The INSERT string is just an example, it's actually something longer. I am a beginner at pgSQL. I've seen some examples but I'm only getting more confused. If you can provide an answer that is also more safe from SQL injection that would be awesome.
One way to do what you're looking for is to compose your INSERT statement dynamically based on the named table. The following function approximates the logic you laid out in the question:
CREATE OR REPLACE FUNCTION smart_insert(table_name TEXT) RETURNS VOID AS $$
DECLARE
target TEXT;
statement TEXT;
BEGIN
CASE table_name
WHEN 'this' THEN target := 'name_id';
WHEN 'that' THEN target := 'lastname_id';
WHEN 'another' THEN target := 'age_id';
END CASE;
statement :=
'INSERT INTO '||table_name||'('||target||') VALUES (nextval(''id''));';
EXECUTE statement;
END;
$$ LANGUAGE plpgsql;
Note that I'm using a sequence to populate these tables (the call to nextval). I'm not sure if that is your use case, but hopefully this example is extensible enough for you to modify it to fit your scenario. A contrived demo:
postgres=# SELECT smart_insert('this');
smart_insert
--------------
(1 row)
postgres=# SELECT smart_insert('that');
smart_insert
--------------
(1 row)
postgres=# SELECT name_id FROM this;
name_id
---------
101
(1 row)
postgres=# SELECT lastname_id FROM that;
lastname_id
-------------
102
(1 row)
Your example doesn't make a lot of sense. Probably over-simplified. Anyway, here is a trigger function for the requested functionality that inserts the new id in a selected column of a target table, depending on the triggering table:
CREATE OR REPLACE FUNCTION smart_insert(table_name TEXT)
RETURNS trigger AS
$func$
BEGIN
EXECUTE
'INSERT INTO table1 ('
|| CASE TG_TABLE_NAME
WHEN 'this' THEN 'name_id'
WHEN 'that' THEN 'lastname_id'
WHEN 'another' THEN 'age_id'
END CASE
||') VALUES ($1)'
USING NEW.id;
END
$func$ LANGUAGE plpgsql;
To refer to the id column of the new row, use NEW.id not id.NEW.
To pass a value to dynamic code, use the USING clause of EXECUTE. This is faster and more elegant, avoids casting to text and back and also makes SQL injection impossible.
Don't use many variables and assignments in plpgsql, where this is comparatively expensive.
If the listed columns of the target table don't have non-default column defaults, you don't even need dynamic SQL:
CREATE OR REPLACE FUNCTION smart_insert(table_name TEXT)
RETURNS trigger AS
$func$
BEGIN
INSERT INTO table1 (name_id, lastname_id, age_id)
SELECT CASE WHEN TG_TABLE_NAME = 'this' THEN NEW.id END
, CASE WHEN TG_TABLE_NAME = 'that' THEN NEW.id END
, CASE WHEN TG_TABLE_NAME = 'another' THEN NEW.id END;
END
$func$ LANGUAGE plpgsql;
A CASE expression without ELSE clause defaults to NULL, which is the default column default.
Both variants are safe against SQL injection.
I have the following script to dynamically create views into a PostgreSQL database.
CREATE OR REPLACE FUNCTION cs_refresh_mviews() RETURNS integer AS $$
DECLARE
mviews RECORD;
query text;
park_name text;
ppstatements int;
BEGIN
RAISE NOTICE 'Creating views...';
FOR mviews IN SELECT name FROM "Canadian_Parks" LOOP
park_name := mviews.name;
RAISE NOTICE 'Creating or replace view %s...', mviews.name;
query := 'CREATE OR REPLACE VIEW %_view AS
SELECT * from "Canadian_Parks" where name=''%'';
ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name;
-- RAISE NOTICE query;
EXECUTE query;
END LOOP;
RAISE NOTICE 'Done refreshing materialized views.';
RETURN 1;
END;
$$ LANGUAGE plpgsql;
I have confirmed integrity of the string, such as
CREATE OR REPLACE VIEW Saguenay_St__Lawrence_view AS
SELECT * from "Canadian_Parks" where name='Saguenay_St__Lawrence';
ALTER TABLE Saguenay_St__Lawrence_view OWNER TO postgres
assigned to the query variable by manually submitting this to the database and getting a successful response.
However, if I attempt to execute the function using
SELECT cs_refresh_mviews();
the followig error is displayed:
ERROR: query "SELECT 'CREATE OR REPLACE VIEW %_view AS SELECT * from "Canadian_Parks" where name=''%''; ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name" returned 4 columns
CONTEXT: PL/pgSQL function "cs_refresh_mviews" line 32 at assignment
********** Error **********
ERROR: query "SELECT 'CREATE OR REPLACE VIEW %_view AS SELECT * from "Canadian_Parks" where name=''%''; ALTER TABLE %_view OWNER TO postgres', park_name, park_name, park_name" returned 4 columns
SQL state: 42601
Context: PL/pgSQL function "cs_refresh_mviews" line 32 at assignment
Why has this been converted to a SELECT statement, instead of a pure CREATE?
You setup is pretty twisted. Why would you save part of the name of a view in a composite type of a table instead of saving it in a plain text column?
Anyhow, it could work like this:
Setup matching question:
CREATE SCHEMA x; -- demo in test schema
SET search_path = x;
CREATE TYPE mviews AS (id int, name text); -- composite type used in table
CREATE TABLE "Canadian_Parks" (name mviews);
INSERT INTO "Canadian_Parks"(name) VALUES
('(1,"canadian")')
,('(2,"islandic")'); -- composite types, seriously?
SELECT name, (name).* from "Canadian_Parks";
CREATE OR REPLACE FUNCTION cs_refresh_mviews()
RETURNS int LANGUAGE plpgsql SET search_path = x AS -- search_path for test
$func$
DECLARE
_parkname text;
BEGIN
FOR _parkname IN SELECT (name).name FROM "Canadian_Parks" LOOP
EXECUTE format('
CREATE OR REPLACE VIEW %1$I AS
SELECT * FROM "Canadian_Parks" WHERE (name).name = %2$L;
ALTER TABLE %1$I OWNER TO postgres'
, _parkname || '_view', _parkname);
END LOOP;
RETURN 1;
END
$func$;
SELECT cs_refresh_mviews();
DROP SCHEMA x CASCADE; -- clean up
Major points
As you are executing text with execute, you need to safeguard against SQL injection. I use the format() function for identifiers and the literal
I use the syntax SELECT (name).name to cope with your weird setup and extract the name we need right away.
Similarly, the VIEW needs to read WHERE (name).name = .. to work in this setup.
I removed a lot of noise that is irrelevant to the question.
It's also probably pointless to have the function RETURN 1. Just define the function with RETURNS void. I kept it, though, to match the question.
Untangled setup
How it probably should be:
CREATE SCHEMA x;
SET search_path = x;
CREATE TABLE canadian_parks (id serial primary key, name text);
INSERT INTO canadian_parks(name) VALUES ('canadian'), ('islandic');
SELECT * from canadian_parks;
CREATE OR REPLACE FUNCTION cs_refresh_mviews()
RETURNS void LANGUAGE plpgsql SET search_path = x AS
$func$
DECLARE
parkname text;
BEGIN
FOR parkname IN SELECT name FROM canadian_parks LOOP
EXECUTE format('
CREATE OR REPLACE VIEW %1$I AS
SELECT * FROM canadian_parks WHERE name = %2$L;
ALTER TABLE %1$I OWNER TO postgres'
, parkname || '_view', parkname);
END LOOP;
END
$func$;
SELECT cs_refresh_mviews();
DROP SCHEMA x CASCADE;
You've misunderstood usage of commas in assignment expression.
It turns query to array (RECORD) instead of scalar.
Use concatenation:
park_name := quote_ident(mviews.name||'_view');
query := 'CREATE OR REPLACE VIEW '||park_name||' AS SELECT * from "Canadian_Parks" where name='||quote_literal(mviews.name)||'; ALTER TABLE '||park_name||' OWNER TO postgres';
I have plpgsql function:
CREATE OR REPLACE FUNCTION test() RETURNS VOID AS
$$
DECLARE
my_row my_table%ROWTYPE;
BEGIN
SELECT * INTO my_row FROM my_table WHERE id='1';
my_row.date := now();
END;
$$ LANGUAGE plpgsql;
I would like to know if it's possible to directly UPDATE my_row record.
The only way I've found to do it now is:
UPDATE my_table SET date=now() WHERE id='1';
Note this is only an example function, the real one is far more complex than this.
I'm using PostgreSQL 9.2.
UPDATE:
Sorry for the confusion, what I wanted to say is:
SELECT * INTO my_row FROM my_table INTO my_row WHERE id='1';
make_lots_of_complicated_modifications_to(my_row, other_complex_parameters);
UPDATE my_row;
I.e. Use my_row to persist information in the underlying table. I have lots of parameters to update.
I would like to know if it's possible to directly update "my_row"
record.
It is.
You can update columns of a row or record type in plpgsql - just like you have it. It should be working, obviously?
This would update the underlying table, of course, not the variable!
UPDATE my_table SET date=now() WHERE id='1';
You are confusing two things here ...
Answer to clarification in comment
I don't think there is syntax in PostgreSQL that can UPDATE a whole row. You can UPDATE a column list, though. Consider this demo:
Note how I use thedate instead of date as column name, date is a reserved word in every SQL standard and a type name in PostgreSQL.
CREATE TEMP TABLE my_table (id serial, thedate date);
INSERT INTO my_table(thedate) VALUES (now());
CREATE OR REPLACE FUNCTION test_up()
RETURNS void LANGUAGE plpgsql AS
$func$
DECLARE
_r my_table;
BEGIN
SELECT * INTO _r FROM my_table WHERE id = 1;
_r.thedate := now()::date + 5 ;
UPDATE my_table t
-- explicit list of columns to be to updated
SET (id, thedate) = (_r.id, _r.thedate)
WHERE t.id = 1;
END
$func$;
SELECT test_up();
SELECT * FROM my_table;
However, you can INSERT a whole row easily. Just don't supply a column list for the table (which you normally should, but in this case it is perfectly ok, not to).
As an UPDATE is internally a DELETE followed by an INSERT anyway, and a function automatically encapsulates everything in a transaction, I don't see, why you couldn't use this instead:
CREATE OR REPLACE FUNCTION x.test_ delins()
RETURNS void LANGUAGE plpgsql AS
$func$
DECLARE
_r my_table;
BEGIN
SELECT * INTO _r
FROM my_table WHERE id = 1;
_r.thedate := now()::date + 10;
DELETE FROM my_table t WHERE t.id = 1;
INSERT INTO my_table SELECT _r.*;
END
$func$;
I managed to get this working in PLPGSQL in a couple of lines of code.
Given a table called table in a schema called example, and a record of the same type declared as _record, you can update all the columns in the table to match the record using the following hack:
declare _record example.table;
...
-- get the columns in the correct order, as a string
select string_agg(format('%I', column_name), ',' order by ordinal_position)
into _columns
from information_schema.columns
where table_schema='example' and table_name='table';
execute 'update example.table set (' || _columns || ') = row($1.*) where pkey=$2'
using _record, _record.pkey;
In the above example, of course, _record.pkey is the table's primary key.
Postgresql has not set row in update.
If you wont update full row you should assign value for each column separately
yes, its possible to update / append the row-type variable,
CREATE OR REPLACE FUNCTION test() RETURNS VOID AS $$
DECLARE
my_row my_table%ROWTYPE;
BEGIN
SELECT * INTO my_row FROM my_table WHERE id='1';
my_row.date := now();
raise notice 'date : %; ',my_row.date;
END;
$$ LANGUAGE plpgsql;
here the raise notice will display the today's date only.
but this will not update the column date in my_table.