Reordering in Hierarchical category structure

I have a category table that use Hierarchical structure with right and left field.

What开发者_StackOverflow should I do if I want to reorder two fields and how should I manage left and right field values?

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Since you're using left and right, you're probably modelling this as a Nested Set. The top answer to this question about nested sets has a nice method for moving nodes.