Decide between Temoporary tables, Nested tables and Arrays

Question

Hello everyone.
I need to convert T-SQL function to PL-SQL.
I have this line in T-SQL:
DECLARE @FTAP TABLE ([Value] [int] PRIMARY KEY NONCLUSTERED NOT NULL, UNIQUE ([Value]ASC )); As I see that, there are several equivalents in PL-SQL:
1. Global temporary table.
2. Nested table.
3. Array.
The table is declared in the function for reusing in the same function.
When the function finished the table should delete.
Also, the table should have index (or primary key...).
What is the best choice?

Answer 1

be careful in directly translating SQL server code to Oracle. they are fundamentally different in terminology and in the way they work.
you can use associated arrays with record types:
SQL> declare
  2     type rec_demo is record (id number, txt varchar2(100));
  3     type tab_demo is table of rec_demo index by binary_integer;
  4     v_tab_demo tab_demo;
  5  begin
  6
  7    v_tab_demo(1).id := 23;
  8    v_tab_demo(1).txt := 'demo';
  9    v_tab_demo(2).id := 54;
10    v_tab_demo(2).txt := 'demo2';
11
12    for i in 1..v_tab_demo.count loop
13       dbms_output.put_line(v_tab_demo(i).txt);
14    end loop;
15
16
17  end;
18  /
demo
demo2you can also use collections in other ways. Most people would advise against using global temporary tables unless there's no other way and even then they'd recommend materialised views etc.
can you elaborate a bit more about how you're using it? if we know what purpose it's being used for we may be able to assist a bit more efficiently.