94 lines
2.3 KiB
MySQL
94 lines
2.3 KiB
MySQL
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--
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-- Insert tree data for new rows
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--
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CREATE OR REPLACE FUNCTION items_tree_ai( )
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RETURNS TRIGGER
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SECURITY DEFINER
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AS $items_tree_ai$
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BEGIN
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INSERT INTO items_tree( item_id_parent , item_id_child , pt_depth )
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VALUES ( NEW.item_id , NEW.item_id , 0 );
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INSERT INTO items_tree( item_id_parent , item_id_child , pt_depth )
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SELECT x.item_id_parent, NEW.item_id, x.pt_depth + 1
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FROM items_tree x WHERE x.item_id_child = NEW.item_id_parent;
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RETURN NEW;
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END;
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$items_tree_ai$ LANGUAGE 'plpgsql';
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CREATE TRIGGER items_tree_ai
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AFTER INSERT ON items FOR EACH ROW
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EXECUTE PROCEDURE items_tree_ai( );
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--
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-- Make sure the changes are OK before updating
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--
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CREATE OR REPLACE FUNCTION items_tree_bu( )
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RETURNS TRIGGER
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SECURITY DEFINER
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AS $items_tree_bu$
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BEGIN
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IF NEW.item_id <> OLD.item_id THEN
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RAISE EXCEPTION 'Changes to identifiers are forbidden.';
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END IF;
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IF NOT OLD.item_id_parent IS DISTINCT FROM NEW.item_id_parent THEN
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RETURN NEW;
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END IF;
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PERFORM 1 FROM items_tree
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WHERE ( item_id_parent , item_id_child ) = ( NEW.item_id , NEW.item_id_parent );
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IF FOUND THEN
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RAISE EXCEPTION 'Update blocked, it would create a loop.';
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END IF;
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RETURN NEW;
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END;
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$items_tree_bu$ LANGUAGE 'plpgsql';
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CREATE TRIGGER items_tree_bu
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BEFORE UPDATE ON items FOR EACH ROW
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EXECUTE PROCEDURE items_tree_bu( );
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--
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-- Update tree data when a row's parent is changed
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--
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CREATE OR REPLACE FUNCTION items_tree_au( )
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RETURNS TRIGGER
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SECURITY DEFINER
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AS $items_tree_au$
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BEGIN
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IF NOT OLD.item_id_parent IS DISTINCT FROM NEW.item_id_parent THEN
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RETURN NEW;
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END IF;
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-- Remove existing lineage for the updated object and its children
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IF OLD.item_id_parent IS NOT NULL THEN
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DELETE FROM items_tree AS te2
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USING items_tree te1
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WHERE te2.item_id_child = te1.item_id_child
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AND te1.item_id_parent = NEW.item_id
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AND te2.pt_depth > te1.pt_depth;
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END IF;
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-- Create new lineage
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IF NEW.item_id_parent IS NOT NULL THEN
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INSERT INTO items_tree ( item_id_parent , item_id_child , pt_depth )
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SELECT te1.item_id_parent , te2.item_id_child , te1.pt_depth + te2.pt_depth + 1
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FROM items_tree te1 , items_tree te2
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WHERE te1.item_id_child = NEW.item_id_parent
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AND te2.item_id_parent = NEW.item_id;
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END IF;
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RETURN NEW;
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END;
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$items_tree_au$ LANGUAGE 'plpgsql';
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CREATE TRIGGER items_tree_au
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AFTER UPDATE ON items FOR EACH ROW
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EXECUTE PROCEDURE items_tree_au( );
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