使用FETCH的PL / SQL Cursor FOR循环

Question

I'm trying to help my friend with his Oracle homework and he has the following problem:

Use a cursor FOR loop to retrieve the blog id, blog url and blog description if the blog id is less than 4 and place it in a cursor variable. Fetch and process each record and insert a row in the table log for each blog id returned.

We're finding it hard to understand but we have the query:

DECLARE
    CURSOR blog_cursor IS SELECT * FROM blog;
BEGIN
  FOR blog_item IN blog_cursor LOOP
    IF( blog_item.blog_id > 4 ) THEN
      -- Insert a row in the "table log"
      INSERT INTO log( log_id, log_url, log_desc )
      VALUES( blog_item.blog_id, blog_item.blog_url, blog_item.blog_desc );
    END IF;
  END LOOP;
END;
/

Table:

blog
    blog_id
    blog_url
    blog_desc

The query does the job, but it doesn't use the FETCH keyword so we don't think it's technically right. The question seems poorly written but how would you answer it using the FETCH keyword? I'm new to PL/SQL but I have experience with SQL.

Answer 1

You did it right and you don't need a fetch, in fact you did the fetch but you did it implicitly, to use a fetch keyword you need a record type and also you will need to open and close the cursor and also check for is it open or not and also check for if it has rows(in the loop), following is another for of your cursor which uses fetch and a record type:

DECLARE
    CURSOR blog_cursor IS SELECT * FROM blog;
    blog_item blog%rowtype;
BEGIN
  OPEN blog_cursor;
  LOOP
    FETCH blog_cursor INTO blog_item;
    EXIT WHEN blog_cursor%NOTFOUND;
    IF( blog_item.blog_id > 4 ) THEN
      -- Insert a row in the "table log"
      INSERT INTO log( log_id, log_url, log_desc )
      VALUES( blog_item.blog_id, blog_item.blog_url, blog_item.blog_desc );
    END IF;
  END LOOP;
  CLOSE blog_cursor;
END;