Say I have this query:
CREATE OR REPLACE FUNCTION select_from_table(table_name varchar(63))
RETURNS SETOF table_name AS
$$
DECLARE
query TEXT := 'SELECT * FROM ' || table_name;
BEGIN
RETURN QUERY EXECUTE query;
END;
$$ LANGUAGE plpgsql;
Now if I try to execute it, I get error: type "table_name" does not exist and that's probably because I can only use the parameters within the function (between the dollar quotes) and not in the return type definition.
The question would be: are there any ways to SELECT from a table by passing its name as a parameter instead of hard coding it to the function? How?
Related
I've created a function like this.
create or replace function pesquisar_imoveis_residenciais_venda()
returns table(preco decimal)
as $$
begin
select preco from casa_venda;
end; $$
language 'plpgsql';
When I call it
select pesquisar_imoveis_residenciais_venda()
I get the column reference preco is ambiguous.
I've visited some related question. But they are too difficult to follow, very complex functions.
The columns defined in the RETURNS QUERY clause are variables in the PL/pgSQL function body, so the ambiguity is between the variable preco and the table column of the same name. You need to qualify the reference with either the table name or the function name to disambiguate that.
But your function definition has other issues. I think you want:
create or replace function pesquisar_imoveis_residenciais_venda()
returns table(preco decimal)
as $$
begin
return query select cv.preco from casa_venda cv;
end; $$
language 'plpgsql';
select *
from pesquisar_imoveis_residenciais_venda();
Here is a db<>fiddle.
You can override the plpgsql.variable_conflict configuration parameter:
create or replace function pesquisar_imoveis_residenciais_venda()
returns table(preco decimal)
as $$
#variable_conflict use_column
begin
select preco from casa_venda;
end; $$
language 'plpgsql';
This assumes you want to use the column value and not the variable value. If that's not the case then specify #variable_conflict use_variable instead.
See the docs for further details.
it means column name Preco in table casa_venda is not exist or exist more than 1 time.
I have this function that should be returning a varying columns, can I get a help on what is wrong with my code?
CREATE OR REPLACE FUNCTION functions.search(column_name VARCHAR(40))
RETURNS SETOF RECORD AS $$
DECLARE
rec RECORD;
BEGIN
RETURN QUERY EXECUTE format('SELECT %I FROM students_table);
END;
$$ LANGUAGE plpgsql;
Call:
SELECT * FROM functions.search(
('Student Id', 'Subect')
) as ("Student Id" bigint, "Subect" text)
Here's my error
ERROR: function functions.search(record) does not exist
LINE 1: SELECT * FROM functions.search(
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
SQL state: 42883
Character: 15
Thank you very much
There are several things wrong here.
First, to support a variable number of arguments, you need a VARIADIC parameters. Then, your format function call is somewhat truncated and syntactical nonsense.
You could experiment with a function like this:
CREATE FUNCTION functions.search(VARIADIC column_names text[]) RETURNS SETOF record
LANGUAGE plpgsql AS
$$BEGIN
RETURN QUERY EXECUTE
format('SELECT %s FROM students_table',
(SELECT string_agg(quote_ident(s), ', ')
FROM unnest(column_names) AS cols(s))
);
END;$$;
You can call it like this:
SELECT *
FROM functions.search('Student Id', 'Subect')
AS ("Student Id" bigint, "Subect" text);
I'm new to pgsql. I just want to use a table name as a function parameter in pgsql.
CREATE OR REPLACE FUNCTION user_test_table_name_as_input (table_name text)
RETURNS VOID
LANGUAGE plpgsql
AS $$
DECLARE
i int;
BEGIN
FOR i IN EXECUTE 'SELECT DISTINCT category FROM' || quote_ident(table_name)
LOOP
RAISE NOTICE '%', i;
END LOOP;
END
$$
When I try to use this function...
SELECT user_test_table_name_as_input (table_name);
...i get this error:
ERROR: column "table_name" does not exist
SQL state: 42703
I read the related threads, like Table name as a PostgreSQL function parameter, but the other proposed solutions (Concatenation, format() ), do not work for me, neither. Any idea?
'table_name' needs quotes as the argument to the call of your stored procedure - it's text.
CREATE OR REPLACE FUNCTION dummytest_insert_trigger()
RETURNS trigger AS
$BODY$
DECLARE
v_partition_name VARCHAR(32);
BEGIN
IF NEW.datetime IS NOT NULL THEN
v_partition_name := 'dummyTest';
EXECUTE format('INSERT INTO %I VALUES ($1,$2)',v_partition_name)using NEW.id,NEW.datetime;
END IF;
RETURN NULL;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION dummytest_insert_trigger()
OWNER TO postgres;
I'm trying to insert using
insert into dummyTest values(1,'2013-01-01 00:00:00+05:30');
But it's showing error as
ERROR: function format(unknown) does not exist
SQL state: 42883
Hint: No function matches the given name and argument types. You might need to add explicit type casts.
Context: PL/pgSQL function "dummytest_insert_trigger" line 8 at EXECUTE statement
I'm unable get the error.
Your function could look like this in Postgres 9.0 or later:
CREATE OR REPLACE FUNCTION dummytest_insert_trigger()
RETURNS trigger AS
$func$
DECLARE
v_partition_name text := quote_ident('dummyTest'); -- assign at declaration
BEGIN
IF NEW.datetime IS NOT NULL THEN
EXECUTE
'INSERT INTO ' || v_partition_name || ' VALUES ($1,$2)'
USING NEW.id, NEW.datetime;
END IF;
RETURN NULL; -- You sure about this?
END
$func$ LANGUAGE plpgsql;
About RETURN NULL:
To ignore result in BEFORE TRIGGER of PostgreSQL?
I would advice not to use mixed case identifiers. With format( .. %I ..) or quote_ident(), you'd get a table named "dummyTest", which you'll have to double quote for the rest of its existence. Related:
Are PostgreSQL column names case-sensitive?
Use lower case instead:
quote_ident('dummytest')
There is really no point in using dynamic SQL with EXECUTE as long as you have a static table name. But that's probably just the simplified example?
You need explicit cast to text:
EXECUTE format('INSERT INTO %I VALUES ($1,$2)'::text ,v_partition_name) using NEW.id,NEW.datetime;
I want to get list of table names present in the view.
So I have created the function with one parameter(view_name) to get table names.
Function : funtion_GetTables_FromView
CREATE OR REPLACE FUNCTION funtion_GetTables_FromView
(
view_Name varchar
)
RETURNS TABLE
(
TableNames varchar
) AS
$BODY$
DECLARE
v_SQL varchar;
BEGIN
v_SQL := 'SELECT Table_Name
FROM INFORMATION_SCHEMA.VIEW_TABLE_USAGE
WHERE View_Name = ''' || view_Name || '''';
RAISE INFO '%',v_SQL;
RETURN QUERY EXECUTE v_SQL;
END;
$BODY$
LANGUAGE PLPGSQL;
Calling function:
select * from funtion_GetTables_FromView('myview');
But getting an error:
ERROR: structure of query does not match function result type
You only showed a part of the error message, the complete error message gives the actual reason:
ERROR: structure of query does not match function result type
Detail: Returned type information_schema.sql_identifier does not match expected type character varying in column 1.
Where: PL/pgSQL function funtion_gettables_fromview(character varying) line 14 at RETURN QUERY
So the column information_schema.table_name is not a varchar column. The immediate fix for this is to cast the column to the required type:
v_SQL := 'SELECT Table_Name::varchar
FROM INFORMATION_SCHEMA.VIEW_TABLE_USAGE
WHERE View_Name = ''' || view_Name || '''';
But the whole function is needlessly complex and error prone. A simply SQL function will do just fine:
CREATE OR REPLACE FUNCTION funtion_GetTables_FromView(v_viewname varchar)
RETURNS TABLE(tablenames varchar)
AS
$$
SELECT table_name
FROM information_schema.view_table_usage
WHERE view_Name = v_viewname;
$$
LANGUAGE sql;
For some reason this does not require the cast to varchar. I suspect this has something to do with running dynamic SQL inside PL/pgSQL.
Unrelated, but: I personally find it pretty useless to prefix a function with function_. It is obvious when using it, that it is a function. Are you prefixing all your classes with class_ and all your methods with method_ in your programming language?