I have the following table with one field of type timestamp.
Create table Test_Timestamp
(
ColumnA timestamp
);
Now inserting some records for demonstration:
INSERT INTO Test_Timestamp VALUES('1900-01-01 01:21:15'),
('1900-01-01 02:11:25'),
('1900-01-01 12:52:10'),
('1900-01-01 03:20:05');
Now I have created function Function_Test with two parameters namely St_time and En_Time which
are of type varchar, In which I only pass the time like 00:00:01. And after that Function has
to return the table with that condition of two time's parameters.
CREATE OR REPLACE FUNCTION Function_Test
(
St_Time varchar,
En_Time varchar
)
RETURNS TABLE
(
columX timestamp
)
AS
$BODY$
Declare
sql varchar;
wher varchar;
BEGIN
wher := 'Where columna BETWEEN '|| to_char(cast(St_Time as time),'''HH24:MI:SS''') ||' AND '|| to_char(cast(En_Time as time),'''HH24:MI:SS''') ||'';
RAISE INFO '%',wher;
sql := 'SELECT * FROM Test_Timestamp ' || wher ;
RAISE INFO '%',sql;
RETURN QUERY EXECUTE sql;
END;
$BODY$
LANGUAGE PLPGSQL;
---Calling function
SELECT * FROM Function_Test('00:00:00','23:59:59');
But getting an error:
ERROR: invalid input syntax for type timestamp: "00:00:01"
LINE 1: ...ELECT * FROM Test_Timestamp where ColumnA BETWEEN '00:00:01'...
You can cast the column to a time: ColumnA::time
You should also not pass a time (or a date, or a timestamp) as a varchar. And you don't need dynamic SQL or a PL/pgSQL function for this:
CREATE OR REPLACE FUNCTION Function_Test(St_Time time, en_Time time)
RETURNS TABLE (columX timestamp)
AS
$BODY$
SELECT *
FROM Test_Timestamp
where columna::time between st_time and en_time;
$BODY$
LANGUAGE sql;
Call it like this:
select *
from Function_Test(time '03:00:00', time '21:10:42');
You can use extract to the hour, minute and second
http://www.postgresql.org/docs/9.3/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT
Related
I am currently working a stored procedure capable of detecting continuity on a specific set of entries..
The specific set of entries is extracted from a sql query
The function takes in two input parameter, first being the table that should be investigated, and the other being the list of ids which should be evaluated.
For every Id I need to investigate every row provided by the select statement.
DROP FUNCTION IF EXISTS GapAndOverlapDetection(table_name text, entity_ids bigint[]);
create or replace function GapAndOverlapDetection ( table_name text, enteity_ids bigint[] )
returns table ( entity_id bigint, valid tsrange, causes_overlap boolean, causes_gap boolean)
as $$
declare
x bigint;
var_r record;
begin
FOREACH x in array $2
loop
EXECUTE format('select entity_id, valid from' ||table_name|| '
where entity_id = '||x||'
and registration #> now()::timestamp
order by valid ASC') INTO result;
for var_r in result
loop
end loop;
end loop ;
end
$$ language plpgsql;
select * from GapAndOverlapDetection('temp_country_registration', '{1,2,3,4}')
I currently get an error in the for statement saying
ERROR: syntax error at or near "$1"
LINE 12: for var_r in select entity_id, valid from $1
You can iterate over the result of the dynamic query directly:
create or replace function gapandoverlapdetection ( table_name text, entity_ids bigint[])
returns table (entity_id bigint, valid tsrange, causes_overlap boolean, causes_gap boolean)
as $$
declare
var_r record;
begin
for var_r in EXECUTE format('select entity_id, valid
from %I
where entity_id = any($1)
and registration > now()::timestamp
order by valid ASC', table_name)
using entity_ids
loop
... do something with var_r
-- return a row for the result
-- this does not end the function
-- it just appends this row to the result
return query
select entity_id, true, false;
end loop;
end
$$ language plpgsql;
The %I injects an identifier into a string and the $1 inside the dynamic SQL is then populated through passing the argument with the using keyword
Firstly, decide whether you want to pass the table's name or oid. If you want to identify the table by name, then the parameter should be of text type and not regclass.
Secondly, if you want the table name to change between executions then you need to execute the SQL statement dynamically with the EXECUTE statement.
I am writing a Postgres function to get the number of new records in a table. Here table name is a variable.
create or replace function dmt_mas_updates(
tb_name text,
days integer)
returns integer as
$$
declare
ct integer;
begin
execute 'select count(*) from $1 where etl_create_dtm > now() - $2 * interval ''1 days'' '
using tb_name, days into ct;
return ct;
end;
$$ LANGUAGE 'plpgsql'
When I call the function with select * from dmt_mas_updates('dmt_mas_equip_store_dim',2);, I got syntax error at $1.
If I run the query directly select count(*) from dmt_mas_equip_store_dim where etl_create_dtm >= interval '3 days', it works correctly.
Why am I getting this error? What did I do wrong?
Per the documentation:
Note that parameter symbols can only be used for data values — if you want to use dynamically determined table or column names, you must insert them into the command string textually.
Use the format() function:
create or replace function dmt_mas_updates(
tb_name text,
days integer)
returns integer as
$$
declare
ct integer;
begin
execute format(
'select count(*) from %I where etl_create_dtm > now() - $1 * interval ''1 days'' ',
tb_name)
using days into ct;
return ct;
end;
$$ LANGUAGE 'plpgsql';
I want to select persons from a table where the date is within a given month.
This is what I have so far, but it's not working:
CREATE OR REPLACE FUNCTION u7()
RETURNS character varying AS
$BODY$
DECLARE
data varchar=`data`;
mes varchar=`2016-11-21`;
incidencia varchar=`expulsions`;
valor varchar;
BEGIN
EXECUTE `SELECT `
||quote_ident(data)
||`FROM `
||quote_ident(incidencia)
||` WHERE data IN(select date_part(`month`, TIMESTAMP $1))`
INTO valor USING mes;
return valor;
END;
$BODY$
LANGUAGE plpgsql;
select * FROM u7();
Clean syntax for what you are trying to do could look like this:
CREATE OR REPLACE FUNCTION u7()
RETURNS TABLE (valor text) AS
$func$
DECLARE
data text := 'data'; -- the first 3 would typically be function parameters
incidencia text := 'expulsions';
mes timestamp = '2016-11-21';
mes0 timestamp := date_trunc('month', mes);
mes1 timestamp := (mes0 + interval '1 month');
BEGIN
RETURN QUERY EXECUTE format(
'SELECT %I
FROM %I
WHERE datetime_column_name >= $1
AND datetime_column_name < $2'
, data, incidencia)
USING mes0, mes1;
END
$func$ LANGUAGE plpgsql;
SELECT * FROM u7();
Obviously, data cannot be a text column and a timestamp or date column at the same time. I use datetime_column_name for the timestamp column - assuming it's data type timestamp.
Aside from various syntax errors, do not use the construct with date_part(). This way you would have to process every row of the table and could not use an index on datetime_column_name - which my proposed alternative can.
See related answers for explanation:
EXECUTE...INTO...USING statement in PL/pgSQL can't execute into a record?
Table name as a PostgreSQL function parameter
How do I match an entire day to a datetime field?
I have dynamicly generated SELECT. I try to return result as SETOF RECORD. Sth like that:
CREATE FUNCTION test(column_name text) RETURNS SETOF RECORD AS $$
DECLARE
row RECORD;
BEGIN
FOR row IN EXECUTE 'SELECT ' || quote_ident(column_name) || ' FROM dates'
LOOP
RETURN NEXT row;
END LOOP;
RETURN;
END;
$$ LANGUAGE 'plpgsql';
When I try:
SELECT * FROM test('column1');
I get this:
ERROR: a column definition list is required for functions returning "record"
I know that column1 is integer type:
SELECT * FROM test('column1') f(a int);
result is correct, because I know that this is going to be Integer type.
When I try:
SELECT * FROM test('column1') f(a varchar);
I get error:
ERROR: wrong record type supplied in RETURN NEXT
DETAIL: Returned type integer does not match expected type character varying in column 1.
Now my question:
What to do to get rid of part of querty where I define types 'f(a int)'. It should by feasible because Postgres knowns what is returned type. I tried with IMMUTABLE options, but unsuccessfully.
You could cast the value to text inside the function, and declare that the function RETURNS SETOF text. You can also return the whole result set at once; no need to iterate explicitly.
CREATE TABLE dates (column1 int, column2 date);
INSERT INTO dates VALUES (1, date '2012-12-22'), (2, date '2013-01-01');
CREATE FUNCTION test(column_name text) RETURNS SETOF text AS $$
BEGIN
RETURN QUERY EXECUTE 'SELECT '
|| quote_ident(column_name) || '::text FROM dates';
END;
$$ LANGUAGE 'plpgsql';
Now SELECT test('column1'); yields:
test
------
1
2
(2 rows)
... and (with my locale settings) SELECT test('column2'); yields:
test
------------
2012-12-22
2013-01-01
(2 rows)
You need to specify OUT parameters corresponding to the columns you want to return.
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?