What is the method for declaring variables and assigning values in Oracle?

In Oracle, variables can be declared using the DECLARE keyword and assigned values using the assignment operator (:=).

For example, here is an example of declaring a variable named “my_var” and assigning it a value of 10:

DECLARE
  my_var NUMBER := 10;
BEGIN
  -- 可以在这里使用my_var变量
END;
/

Note that variables declared within a PL/SQL block are only visible within that block. If you want to use the same variable in multiple PL/SQL blocks, you can declare the variable in an outer block or use a stored procedure or function to share the variable.