Added more tables for weights and discrete quantities

web/backend/migrations/2024-02-06-144906_create_items_table/up.sql

@@ -6,4 +6,22 @@
 -- items. This table defines the items that are tracked and managed by the system.
 -- An item can be movable or immovable.
 -- An example of an Item may be a measurement device, a tube potentially containing a sample,
--- or a sample itself.
+-- or a sample itself.
+CREATE TABLE items (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  name TEXT NOT NULL,
+  description TEXT,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  created_by UUID NOT NULL,
+  updated_by UUID NOT NULL,
+  project_id UUID NOT NULL,
+  parent_id UUID,
+  location_id UUID,
+  FOREIGN KEY (created_by) REFERENCES users(id),
+  FOREIGN KEY (updated_by) REFERENCES users(id),
+  FOREIGN KEY (project_id) REFERENCES projects(id),
+  FOREIGN KEY (parent_id) REFERENCES items(id),
+  FOREIGN KEY (item_type_id) REFERENCES item_types(id),
+  FOREIGN KEY (location_id) REFERENCES locations(id)
+);

web/backend/migrations/2024-02-09-143242_create_item_weights_table/down.sql

@@ -0,0 +1 @@
+-- This file should undo anything in `up.sql`

web/backend/migrations/2024-02-09-143242_create_item_weights_table/up.sql

@@ -0,0 +1,18 @@
+-- SQL defining the item_weights table.
+-- Each item, being a physical object, has a weight. This table defines the weights of items.
+-- The weight of an item may change over time, and be measured using different scales and by
+-- different people.
+CREATE TABLE item_weights (
+    id SERIAL PRIMARY KEY,
+    item_id INTEGER REFERENCES items(id),
+    weight DECIMAL(10, 2) NOT NULL,
+    weight_unit_id INTEGER REFERENCES weight_units(id),
+    sensor_id INTEGER REFERENCES items(id),
+    measured_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    measured_by INTEGER REFERENCES users(id),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_by INTEGER NOT NULL REFERENCES users(id),
+    updated_by INTEGER NOT NULL REFERENCES users(id),
+    FOREIGN KEY (item_id, weight_unit_id) REFERENCES items(item_id, weight_unit_id),
+);

web/backend/migrations/2024-02-09-144314_create_item_quantities_table/down.sql

@@ -0,0 +1 @@
+-- This file should undo anything in `up.sql`

web/backend/migrations/2024-02-09-144314_create_item_quantities_table/up.sql

@@ -0,0 +1,21 @@
+-- SQL defining the item_quantities table.
+-- Some items may be counted discretely, as opposed to a weight in grams.
+-- This table defines the discrete quantities of items that we have in stock.
+-- The quantity of an item may change over time, so multiple quantity entries
+-- may be inserted for the same item.
+-- While these quantities are discrete, in order to facilitate the semantics of
+-- the system, we will still allow for the user to specify the counter unit for 
+-- the item. For example, a counter unit may be a box, a tube, or a vial.
+CREATE TABLE item_quantities (
+    id SERIAL PRIMARY KEY,
+    item_id INTEGER REFERENCES items(id),
+    quantity INTEGER NOT NULL,
+    unit_id INTEGER REFERENCES weight_units(id),
+    measured_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    measured_by INTEGER REFERENCES users(id),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_by INTEGER NOT NULL REFERENCES users(id),
+    updated_by INTEGER NOT NULL REFERENCES users(id),
+    FOREIGN KEY (item_id, unit_id) REFERENCES item_units(item_id, unit_id),
+);