How to return rows from a declare/begin/end block in Oracle? - sql

Question

I want to return rows from a select statement within a declare/begin/end block. I can do this in T-SQL but I would like to know how to do it in PL/SQL.
The code looks a bit like the following:
declare
blah number := 42;
begin
select *
from x
where x.value = blah;
end;

Answer 1

An anonymous PL/SQL block, like the one you've shown, can't "return" anything. It can interact with the caller by means of bind variables, however.
So the method I would use in this case would be to declare a cursor reference, open it in the PL/SQL block for the desired query, and let the calling application fetch rows from it. In SQLPlus this would look like:
variable rc refcursor
declare
blah number := 42;
begin
open :rc for
select *
from x
where x.value = blah;
end;
/
print x
If you recast your PL/SQL as a stored function then it could return values. In this case what you might want to do is create a collection type, fetch all the rows into a variable of that type, and return it:
CREATE TYPE number_table AS TABLE OF NUMBER;
CREATE FUNCTION get_blah_from_x (blah INTEGER)
RETURN number_table
IS
values number_table;
BEGIN
SELECT id
BULK COLLECT INTO values
FROM x
WHERE x.value = blah;
RETURN values;
END;
/

Answer 2

Well, this depends heavily on your data access library.
You can return any SQL-compatible type as a parameter. This includes complex SQL types and collection types.
But most libraries are simply not capable of handling Oracle's object types.
Either way, my examples will use these object types:
create type SomeType as object(Field1 VarChar(50));
create type SomeTypeList as table of SomeType;
When your access library can handle object types, you could simply return a list of PL/SQL objects:
begin
:list := SomeTypeList(SomeType('a'),SomeType('b'),SomeType('c'));
end;
If not, you could hack around it by forcing this list into a select and return its result as a cursor:
declare
list SomeTypeList;
begin
list := SomeTypeList(SomeType('a'),SomeType('b'),SomeType('c'));
open :yourCursor for
SELECT A
FROM table(list);
end;