sql BULK COLLECT

BULK COLLECT is a feature in SQL that allows you to retrieve multiple rows of data from a SELECT statement into a collection in a single operation. It improves performance by reducing context switches between the SQL engine and the PL/SQL engine.

Here's an example of how to use BULK COLLECT:

DECLARE
  TYPE emp_name_list IS TABLE OF employees.first_name%TYPE;
  emp_names emp_name_list;
BEGIN
  SELECT first_name
  BULK COLLECT INTO emp_names
  FROM employees;
  
  -- Process the retrieved data
  FOR i IN 1..emp_names.COUNT LOOP
    DBMS_OUTPUT.PUT_LINE(emp_names(i));
  END LOOP;
END;

In the above example, the SELECT statement retrieves the first names of employees from the "employees" table and stores them in the "emp_names" collection using BULK COLLECT. The retrieved data can then be processed using a loop or any other required logic.

Using BULK COLLECT can significantly improve the performance when dealing with large result sets in PL/SQL.