This is my query.
select origindept, `count(am_course_name)` as total_course
from am_courseoffered
group by origindept;
I am trying to create a function who will return this query.
CREATE OR REPLACE FUNCTION getcourse ()
RETURNS TABLE (
course_origindept character varying,
course_ count(am_course_name) character varying
)
AS $$
BEGIN
RETURN QUERY select origindept, count(am_course_name) as number_total_course
from am_courseoffered
group by origindept;
END; $$
LANGUAGE 'plpgsql';
There are some error in my function.
ERROR: syntax error at or near "character"
LINE 4: course_ count(am_course_name) character varying
How i create function who will return this query.
Off the top of my head, the count function should return a datatype of bigint, so I would think declaring the count as a varchar would cause a datatype mismatch. Something like this should fix that:
CREATE OR REPLACE FUNCTION getcourse ()
RETURNS TABLE (
course_origindept character varying,
course_count bigint -- change here
) AS $$
BEGIN
RETURN QUERY
select origindept, count(am_course_name) as number_total_course
from am_courseoffered
group by origindept;
END;
$$
LANGUAGE plpgsql;
I do have to ask, though... is this an academic exercise to understand functions? The use case is questionable enough, as a view would be more appropriate.
Related
I want to create a function that can dynamically insert any data type value into any table and multiple columns. But my function can only insert one value to one column:
CREATE OR REPLACE FUNCTION public.dynamic_insert(
tablename character varying,
columname character varying,
datatype character varying,
valuee text
)
RETURNS void
LANGUAGE 'plpgsql'
COST 100
VOLATILE AS
$BODY$
begin
Execute format('insert into %I ('||columname||')
values (cast($1 as '||datatype||'))',tablename,columname);
end;
$BODY$;
Can any one help?
I don't understand your idea clearly. I guess that you want to write one function to insert into table with list of column and values you specify.
If I guess correctly. I suggest some function like this:
CREATE OR REPLACE FUNCTION public.dynamic_insert(
tablename character varying,
columname character varying[],
datatype character varying[],
valuee character varying[]
)
RETURNS void AS
$BODY$
DECLARE
var_sql varchar;
var_sql_column varchar := '';
var_sql_values varchar := '';
begin
var_sql_column := CONCAT('("',ARRAY_TO_STRING(columname, '","'),'")');
FOR i IN 1..ARRAY_LENGTH(columname,1)
LOOP
var_sql_values := var_sql_values || quote_literal(valuee[i]) || '::' || datatype[i] || ',';
END LOOP;
var_sql_values := CONCAT('(',regexp_replace(var_sql_values, ',$', '', 'g'),')');
var_sql := CONCAT('INSERT INTO ', quote_ident(tablename), var_sql_column, ' VALUES ', var_sql_values);
IF (var_sql IS NOT NULL) THEN
EXECUTE(var_sql);
END IF;
end;
$BODY$;
LANGUAGE 'plpgsql'
COST 100
VOLATILE;
Hopefully it matches your require.
p/s: with my experience, just choose one solution between Format, and String concatenation, don't use both in one query, it makes me hard to view and find bug.
------------- Update for question below -----------------------------------
For the Loop please refer the document here
Basically, it will run from 1 to n (with n is the number elements in array) and build a query.
One simple thing to view how it run is you can put some print out data into you function, such as RAISE. Please refer it document here
I have a function like this
CREATE OR REPLACE FUNCTION factors_apart_sa()
RETURNS TABLE(surf_area integer, sa_factor numeric) AS
$BODY$
BEGIN
RETURN QUERY SELECT factors_apart_sa.surf_area, factors_apart_sa.sa_factor FROM factors_apart_sa;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;
After calling this function I get an error:
column reference "factors_apart_sa.surf_area" is ambiguous
How come is it still ambiguous if I have specified the table name.
Here is the table factors_apart_sa:
CREATE TABLE factors_apart_sa
(
factors_apar_sa_id bigserial NOT NULL,
surf_area integer,
sa_factor numeric(19,4) NOT NULL
)
Use a table alias:
CREATE OR REPLACE FUNCTION factors_apart_sa()
RETURNS TABLE(surf_area integer, sa_factor numeric) AS
$BODY$
BEGIN
RETURN QUERY SELECT f.surf_area, f.sa_factor FROM factors_apart_sa f;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
It is not a good idea to have the same names for a table and a function;
To call a function returnig set of rows place it in a FROM clause:
select f.*
from factors_apart_sa() f;
I've got a postgresql stored procedure, which is returning an integer.
When I call that function, the result is returned with the function name as column name.
For example the name of the function is: "add-person". The column name, when invoking the function, is "add-person".
Is there a way to make the database return the integer with a self-choosen column name? For example "id"?
I think it is pretty easy, but I currently miss the forests for the trees..
Edit:
What i'd missed to tell, is that the return value is a variable, like so:
CREATE OR REPLACE FUNCTION "scheme"."add-person"(arggivenname character varying, argfamilyname character varying) RETURNS integer AS
$BODY$
DECLARE
varResponse integer;
BEGIN
-- Operations before
INSERT INTO "scheme"."table"
(
given_name,
family_name
)
VALUES
(
arggivenname,
argfamilyname
)
RETURNING
"id"
INTO
varResponse;
-- Operations after
RETURN varResponse;
END;
$BODY$
LANGUAGE plpgsql VOLATILE COST 100;
You can us the AS statement for that. That means:
Select add-person() AS yourcolumnname
To have a named column from a function it is necessary to create a type and return that type from the function
create type mytype as (mycolumn integer);
create or replace function ri()
returns mytype as $$
select 1;
$$ language sql;
select * from ri();
mycolumn
----------
1
Edit
Or much simpler without the type creation as in #pozs comment:
create or replace function ri(out mycolumn integer)
as $$
select 1;
$$ language sql;
I have the table with some columns:
--table
create table testz
(
ID uuid,
name text
);
Note: I want to insert ID values by passing as a parameter to the function. Because I am generating the ID value
in the front end by using uuid_generate_v4(). So I need to pass the generated value to the function to insert
into the table
My bad try:
--function
CREATE OR REPLACE FUNCTION testz
(
p_id varchar(50),
p_name text
)
RETURNS VOID AS
$BODY$
BEGIN
INSERT INTO testz values(p_id,p_name);
END;
$BODY$
LANGUAGE PLPGSQL;
--EXECUTE FUNCTION
SELECT testz('24f9aa53-e15c-4813-8ec3-ede1495e05f1','Abc');
Getting an error:
ERROR: column "id" is of type uuid but expression is of type character varying
LINE 1: INSERT INTO testz values(p_id,p_name)
You need a simple cast to make sure PostgreSQL understands, what you want to insert:
INSERT INTO testz values(p_id::uuid, p_name); -- or: CAST(p_id AS uuid)
Or (preferably) you need a function, with exact parameter types, like:
CREATE OR REPLACE FUNCTION testz(p_id uuid, p_name text)
RETURNS VOID AS
$BODY$
BEGIN
INSERT INTO testz values(p_id, p_name);
END;
$BODY$
LANGUAGE PLPGSQL;
With this, a cast may be needed at the calling side (but PostgreSQL usually do better automatic casts with function arguments than inside INSERT statements).
SQLFiddle
If your function is that simple, you can use SQL functions too:
CREATE OR REPLACE FUNCTION testz(uuid, text) RETURNS VOID
LANGUAGE SQL AS 'INSERT INTO testz values($1, $2)';
I have a function in pgsql
CREATE OR REPLACE FUNCTION core.date_bs_from_ad(date_in_ad date)
RETURNS character varying AS
$$
BEGIN
RETURN(
SELECT date_in_bs FROM core.date_conversion
WHERE date_in_ad = $1
);
END
$$
LANGUAGE plpgsql;
It is created with no errors, but when i use this function it through following error:
ERROR: column reference "date_in_ad" is ambiguous
LINE 3: WHERE date_in_ad = $1
^
DETAIL: It could refer to either a PL/pgSQL variable or a table column.
QUERY: SELECT (
SELECT MAX(date_in_bs) FROM core.date_conversion
WHERE date_in_ad = $1
)
CONTEXT: PL/pgSQL function core.date_bs_from_ad(date) line 3 at RETURN
********** Error **********
ERROR: column reference "date_in_ad" is ambiguous
SQL state: 42702
Detail: It could refer to either a PL/pgSQL variable or a table column.
Context: PL/pgSQL function core.date_bs_from_ad(date) line 3 at RETURN
In cases like these, where the code is simple straightforward enough, sometimes it is useful to rely on one of these special plpgsql commands at the start of the function text:
#variable_conflict error
#variable_conflict use_variable
#variable_conflict use_column
In this case, it would be used as follows:
CREATE OR REPLACE FUNCTION core.date_bs_from_ad(date_in_ad date)
RETURNS character varying AS
$$
#variable_conflict use_column
BEGIN
RETURN(
SELECT date_in_bs FROM core.date_conversion
WHERE date_in_ad = $1
);
END
$$
This is especially useful for cases when the clash is not with the parameters, but rather with the output column names, such as this:
CREATE OR REPLACE FUNCTION core.date_bs_from_ad(p_date_in_ad date)
RETURNS TABLE (date_in_bs character varying) AS
$$
BEGIN
RETURN QUERY
SELECT date_in_bs FROM core.date_conversion
WHERE date_in_ad = p_date_in_ad;
END;
$$
The function above will fail because it the compiler cannot decide if date_in_bs is the output variable name or one of core.date_conversion's columns. For problems like these, the command #variable_conflict use_column can really help.
There is a collision between SQL identifier and PlpgSQL variable. There are no clean, what do you want. You wrote a predicate, that is TRUE always.
Good to use:
prefix (usually "_") for local variables
qualified names in embedded SQL - like table_name.column_name
so both techniques (only one is necessary)
CREATE OR REPLACE FUNCTION core.date_bs_from_ad(_date_in_ad date)
RETURNS character varying AS $$
BEGIN
RETURN SELECT dc.date_in_bs
FROM core.date_conversion dc
WHERE dc.date_in_ad = _date_in_ad;
END
$$ LANGUAGE plpgsql;
For these one line functions is SQL language better:
CREATE OR REPLACE FUNCTION core.date_bs_from_ad(_date_in_ad date)
RETURNS character varying AS $$
SELECT dc.date_in_bs
FROM core.date_conversion dc
WHERE dc.date_in_ad = $1;
$$ LANGUAGE sql;