EXPLAIN EXTENDED

This is article 5 of 6 on linked lists in MySQL:

• Sorting lists
• Sorting lists: moving items
• Sorting lists: adding items
• Sorting lists: deleting items
• Sorting lists: moving blocks
• Sorting lists: deleting blocks

Now, let's discuss the mass updates.

In some user interfaces it is needed sometimes to select a whole block of items and move it towards the top or the bottom of the list all at once.

This may be useful to manage MP3 playlists, photo stacks, etc.

With linked lists, it's quite simple. Just like in case of moving a single item, we need to update only three rows.

Moving the items in block, though, requires some more checking:
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