How to populate nested object table in pl/sql block? - oracle

Question

I struggle a problem, which, i think, is rather simple.
I have a type T_OPERATION_TAG in a database which is created as:
CREATE OR REPLACE TYPE t_operation_tag AS OBJECT(
tag_name VARCHAR2(30),
tag_value VARCHAR2(30),
CONSTRUCTOR FUNCTION t_operation_tag RETURN SELF AS RESULT
)
I also have another type T_OPERATION_TAGS, which is defined as follows
CREATE OR REPLACE TYPE t_operation_tags AS TABLE OF t_operation_tag;
Then in my pl/sql block i have the following code
DECLARE
p_op_tags t_operation_tags;
BEGIN
p_op_tags := t_operation_tags();
FOR i IN (SELECT tag_name, tag_value
FROM op_tags_table
WHERE some_condition)
LOOP
--How to append new lines to p_op_tags ?
END LOOP;
END;
So, if the SELECT-query in the FOR LOOP returns,e.g., five lines then how can I populate my P_OP_TAGS object table with these five lines?

Answer 1

Like this:
DECLARE
p_op_tags t_operation_tags;
p_cursor sys_refcursor;
p_limit number := 5;
BEGIN
open p_cursor for
SELECT t_operation_tag(tag_name, tag_value)
FROM op_tags_table
;
fetch p_cursor bulk collect into p_op_tags limit p_limit;
DBMS_OUTPUT.put_line(p_op_tags(4).tag_name);
close p_cursor;
END;
Or if you prefer the loop clause:
DECLARE
p_op_tag t_operation_tag;
p_op_tags t_operation_tags;
p_limit number := 5;
BEGIN
p_op_tags := t_operation_tags();
for i in (SELECT tag_name, tag_value
FROM op_tags_table
WHERE some_condition
and rownum < p_limit + 1)
loop
p_op_tag := t_operation_tag(i.tag_name, i.tag_value);
p_op_tags.extend();
p_op_tags(p_op_tags.COUNT) := p_op_tag;
end loop;
DBMS_OUTPUT.put_line(p_op_tags(4).tag_name);
END;
/

Answer 2

You don't really need a cursor or loop at all, if you're populating the collection entirely from your query; you can bulk collect straight into it:
DECLARE
p_op_tags t_operation_tags;
BEGIN
SELECT t_operation_tag(tag_name, tag_value)
BULK COLLECT INTO p_op_tags
FROM op_tags_table
WHERE some_condition;
...
END;
/