48 lines
1.6 KiB
MySQL
48 lines
1.6 KiB
MySQL
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-- SPDX-FileCopyrightText: 2024 Simon Bruder <simon@sbruder.de>
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--
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-- SPDX-License-Identifier: AGPL-3.0-or-later
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-- generic is a category of products (like CR2032 3 V battery)
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-- or a product where details do not matter (like USB-A to USB-Micro-B cable 1 m)
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-- specific is a concrete model of product (like Panasonic DL2032)
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CREATE TYPE item_class_type AS ENUM ('generic', 'specific');
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CREATE TABLE item_classes (
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id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
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name VARCHAR NOT NULL,
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type item_class_type NOT NULL DEFAULT 'generic',
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parent UUID REFERENCES item_classes(id),
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CONSTRAINT parent_only_for_specific CHECK (type = 'generic' AND parent IS NULL OR type = 'specific' AND parent IS NOT NULL)
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);
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INSERT INTO item_classes (id, name) values ('afd0e9bd-c4df-425e-8af4-6b5b0326a4ae', 'Default Item Class');
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ALTER TABLE items
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ADD class UUID NOT NULL REFERENCES item_classes(id) DEFAULT 'afd0e9bd-c4df-425e-8af4-6b5b0326a4ae';
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ALTER TABLE items
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ALTER class DROP DEFAULT;
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DELETE FROM item_classes
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WHERE (id = 'afd0e9bd-c4df-425e-8af4-6b5b0326a4ae'
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AND NOT EXISTS (SELECT 1 FROM items WHERE class = 'afd0e9bd-c4df-425e-8af4-6b5b0326a4ae' LIMIT 1));
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CREATE FUNCTION check_item_class_parent()
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RETURNS TRIGGER AS $$
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BEGIN
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IF NEW.parent IS NULL THEN
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RETURN NEW;
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END IF;
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IF (SELECT type FROM item_classes WHERE id = NEW.parent) = 'generic' THEN
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RETURN NEW;
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END IF;
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RAISE EXCEPTION 'Specific item classes may only have a generic parent (to avoid recursion)';
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END;
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$$ LANGUAGE plpgsql;
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CREATE TRIGGER prevent_item_class_recursion
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BEFORE INSERT OR UPDATE ON item_classes
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FOR EACH ROW
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EXECUTE FUNCTION check_item_class_parent();
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