I have a postgresql function
CREATE OR REPLACE FUNCTION fixMissingFiles() RETURNS VOID AS $$
DECLARE
deletedContactId integer;
BEGIN
SELECT INTO deletedContactId contact_id FROM myContacts WHERE id=206351;
-- print the value of deletedContactId variable to the console
END;
$$ LANGUAGE plpgsql;
How can I print the value of the deletedContactId to the console?
You can raise a notice in Postgres as follows:
RAISE NOTICE 'Value: %', deletedContactId;
Read here for more details.
Also, the SELECT INTO you're using looks like PostgreSQL for copying rows into a table. See, for example, the SELECT INTO doc page which state: "SELECT INTO -- define a new table from the results of a query"
In pgplSQL I'm used to seeing it in this order: SELECT INTO ... so your first line should probably be:
SELECT contact_id INTO deletedContactId FROM myContacts WHERE id=206351;
As described in Executing a Query with a Single-Row Result.
Related
I keep getting the "SELECT query has no destination for result data" error upon calling this test procedure. What am I doing wrong? I did try adding the RETURN() command prior to SELECT statement but that didn't work either.
CREATE OR REPLACE PROCEDURE SchemaName.SP_Testing_Creating_Procedure (OUT ColumnName VARCHAR(9))
AS $$
BEGIN
SELECT TOP 10 ColumnName FROM SchemaName.TableName where ColumnName is not null;
END;
$$
LANGUAGE plpgsql;
CALL SchemaName.SP_Testing_Creating_Procedure();
As John mentioned you need to put the result into OUT column, examples of using IN, OUT and INOUT parameters you can find here
But if you need to return a few rows as a result, you have to use refcursor
as it's described here
CREATE OR REPLACE PROCEDURE SchemaName.SP_Testing_Creating_Procedure (INOUT result refcursor)
AS $$
BEGIN
OPEN result FOR
SELECT TOP 10 ColumnName
FROM SchemaName.TableName
WHERE ColumnName IS NOT null;
END;
$$
LANGUAGE plpgsql;
Then you can call the stored procedure in a transaction
BEGIN;
CALL logs.SP_Testing_Creating_Procedure('mycursor');
FETCH ALL FROM mycursor;
COMMIT;
another option is temp table which is also described in the above doc
Your procedure is running a SELECT command, but it is not doing anything with the results.
If your intention was to return a result set, you will need to put data in the OUT column.
See: Returning a result set - Amazon Redshift
So, i need to create a function that returns the count of the lines in a table, the table name must be specified by the user. This is the code i have:
CREATE OR REPLACE FUNCTION datiInTab( table regclass )
RETURNS NUMERIC(5) AS
$$
DECLARE
num NUMERIC(5);
cmd VARCHAR(1000):='SELECT COUNT(*) FROM ';
BEGIN
EXECUTE cmd || table;
RETURN num;
END;
$$
LANGUAGE plpgsql;
SELECT * FROM datiInTab(corsi);
And this is the error that returns after i execute:
ERROR: ERRORE: la colonna "corsi" non esiste
LINE 1: SELECT * FROM datiInTab(corsi); ^ SQL state: 42703 Character: 25
Meaning that the column "corsi" doesn't exist.
I debugged as much as i could and the only conclusion is that i don't really know what i need to do in order to make use of this dynamic call.
edit: regclass was a last minute addition, after trying with a simple varchar, that returned the same exact error
You can't name a variable table. it is a reserved word
and you have to pass a string else postgres thinks you want to pass a column
CREATE OR REPLACE FUNCTION datiInTab( table1 regclass )
RETURNS NUMERIC(5) AS
$$
DECLARE
num NUMERIC(5);
cmd VARCHAR(1000):='SELECT COUNT(*) FROM ';
BEGIN
EXECUTE cmd || table1;
RETURN num;
END;
$$
LANGUAGE plpgsql;
✓
SELECT * FROM datiInTab('corsi');
ERROR: relation "corsi" does not exist
LINE 1: SELECT * FROM datiInTab('corsi');
^
db<>fiddle here
How is it possible to send a query to all databases on a server? I do not want to input all databases names, the script should auto-detect them.
example query:
SELECT SUM(tourney_results.amt_won)-SUM((tourney_summary.amt_buyin+tourney_summary.amt_fee)) as results
FROM tourney_results
INNER JOIN tourney_summary
ON tourney_results.id_tourney=tourney_summary.id_tourney
Where id_player=(SELECT id_player FROM player WHERE player_name='Apple');
So what I want to achieve here, if there is 2 databases, the first one would result 60, the second one would result 50, I need the 55 output here.
All databeses would have the same structure, tables etc.
You can do it using plpgsql and db_link. First install the db_link extension in the database you are connecting to:
CREATE EXTENSION dblink;
Then use a plpgsql function which iterates over all database on the server and executes the query. See this example (see comments inline). Note that I used a sample query in the function. You have to adapt the function with your real query:
CREATE or REPLACE FUNCTION test_dblink() RETURNS BIGINT AS
$$
DECLARE pg_database_row record;
query_result BIGINT;
_dbname TEXT;
_conn_name TEXT;
return_value BIGINT;
BEGIN
--initialize the final value
return_value = 0;
--first iterate over the records in the meta table pg_database
FOR pg_database_row in SELECT * FROM pg_database WHERE (NOT datistemplate) AND (datallowconn) LOOP
_dbname = pg_database_row.datname;
--build a connection name for db_link
_conn_name=_dbname||'myconn';
--close the connection is already active:
IF array_contains(dblink_get_connections(),_conn_name) THEN
PERFORM dblink_disconnect(_conn_name);
END IF;
-- open the connection with the actual database name
PERFORM dblink_connect(_dbname||'myconn', 'dbname='||_dbname);
-- check if the table does exist in the database:
PERFORM * FROM dblink(_conn_name,'SELECT 1 from pg_tables where tablename = ''your_table''') AS t(id int) ;
IF FOUND THEN
-- if the table exist, perform the query and save the result in a variable
SELECT * FROM dblink(_conn_name,'SELECT sum(id) FROM your_table limit 1') AS t(total int) INTO query_result;
IF query_result IS NOT NULL THEN
return_value = return_value + query_result;
END IF;
END IF;
PERFORM dblink_disconnect(_conn_name);
END LOOP;
RETURN return_value;
END;
$$
LANGUAGE 'plpgsql';
Execute the function with
select test_dblink();
i've implemented a function that check if a value appears in a specific row of a specific table:
CREATE FUNCTION check_if_if_exist(id INTEGER, table_name character(50), table_column character(20) ) RETURNS BOOLEAN AS $$
DECLARE res BOOLEAN;
BEGIN
SELECT table_column INTO res
FROM table_name
WHERE table_column = id;
RETURN res;
END;
$$ LANGUAGE plpgsql
i've create and fill a simple test table for try this function:
CREATE TABLE tab(f INTEGER);
and i call function like
SELECT check_if_exist(10, tab, f);
but i occurs in this error:
ERROR: column "prova" does not exist
LINE 1: SELECT check_if_exist(10, tab, f);
^
********** Error **********
ERROR: column "tab" does not exist
SQL state: 42703
Character: 27
why?
In addition to Elmo response you must be careful with types. You have got:
ERROR: column "tab" does not exist
because SQL parser do not know how to deal with tab which is without quote. Your query must be like:
SELECT check_if_exist(10, 'tab', 'f');
As Elmo answered you use dynamic query, so even if you quote tab you will got error:
ERROR: relation "table_name" does not exist
so you can use EXECUTE, example:
CREATE OR REPLACE FUNCTION check_if_exist(id INTEGER, table_name varchar, table_column varchar) RETURNS BOOLEAN AS $$
DECLARE
sql varchar;
cnt int;
BEGIN
sql := 'SELECT count(*) FROM ' || quote_ident(table_name) || ' WHERE ' || quote_ident(table_column) || '=$1';
RAISE NOTICE 'sql %', sql;
EXECUTE sql USING id INTO cnt;
RETURN cnt > 0;
END;
$$ LANGUAGE plpgsql
You can also use VARCHAR instead of character(N) in function arguments and use CREATE OR REPLACE FUNCTION ... instead of just CREATE FUNCTION ... which is very handy at debugging.
Your code has no chance to work - when dealing with different tables in PLPGSQL you need to utilize dynamic queries, so EXECUTE is required - http://www.postgresql.org/docs/current/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN
But first of all - there is nothing bad in using PostgreSQL EXISTS - http://www.postgresql.org/docs/current/static/functions-subquery.html#AEN15284 instead of inventing your own - performance of your solution will be significantly worse than using included batteries...
Hopefully this is helpful. Good luck.
I am using Postgresql 8.3 and have the following simple function that will return a refcursor to the client
CREATE OR REPLACE FUNCTION function_1() RETURNS refcursor AS $$
DECLARE
ref_cursor REFCURSOR;
BEGIN
OPEN ref_cursor FOR SELECT * FROM some_table;
RETURN (ref_cursor);
END;
$$ LANGUAGE plpgsql;
Now , I can use the following SQL commands to call this function and manipulate the returned cursor ,but the cursor name is automatically generated by the PostgreSQL
BEGIN;
SELECT function_1(); --It will output the generated cursor name , for example , "<unnamed portal 11>" ;
FETCH 4 from "<unnamed portal 11>";
COMMIT;
Besides explicitly declaring the cursor name as the input parameter of the function as described by 38.7.3.5. Returning Cursors, can I declare my own cursor name and use this cursor name to manipulate the returned cursor instead of Postgresql automatically generates for me ?
If not, are there any commands that can get the generated cursor name ?
I'm not quite sure from wich version of Postgre this is available (in 8.4 it is valid) but i found quite easiest to define the cursor name when you declare it, like this:
CREATE OR REPLACE FUNCTION function_1() RETURNS refcursor AS $$
DECLARE
ref_cursor REFCURSOR := 'mycursor';
BEGIN
OPEN ref_cursor FOR SELECT * FROM some_table;
RETURN (ref_cursor);
END;
$$ LANGUAGE plpgsql;
And then you can get it like this:
BEGIN;
SELECT function_1();
FETCH 4 from mycursor;
COMMIT;
I find this method less cumbersome.
Hope that helps.
Yes, use:
CREATE OR REPLACE FUNCTION function_1(refcursor) RETURNS refcursor AS $$
BEGIN
OPEN $1 FOR SELECT * FROM some_table;
RETURN $1;
END;
$$ LANGUAGE plpgsql;
Result:
SELECT function_1('myowncursorname');
function_1
-----------------
myowncursorname
(1 row)
It looks like auto-generated name is <unnamed portal n>, where n is natural number (from 1).
EDIT:
As another way you could use pg_cursors view with such query to obtain generated cursor name:
SELECT name FROM pg_cursors WHERE statement LIKE 'SELECT * FROM some_table';
For example:
BEGIN;
SELECT function_1();
SELECT name FROM pg_cursors WHERE statement LIKE 'SELECT * FROM some_table';
COMMIT;
Result:
function_1
--------------------
<unnamed portal 3>
(1 row)
name
--------------------
<unnamed portal 3>
(1 row)