Update: 2026-05-15 04:35:25

database/migrations/008_invoice_lines_enhance.sql

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+-- ══════════════════════════════════════════════════
+-- Migration 008: Enhance invoice_lines for tax classification
+-- Adds tax_amount, discount_amount, net_total, tax_category
+-- ══════════════════════════════════════════════════
+
+-- Add tax_amount column (calculated from tax_rate × line_total)
+ALTER TABLE invoice_lines
+  ADD COLUMN IF NOT EXISTS tax_amount DECIMAL(12,3) DEFAULT 0 AFTER tax_rate;
+
+-- Add discount_amount column  
+ALTER TABLE invoice_lines
+  ADD COLUMN IF NOT EXISTS discount_amount DECIMAL(12,3) DEFAULT 0 AFTER tax_amount;
+
+-- Add net_total column (subtotal + tax - discount)
+ALTER TABLE invoice_lines
+  ADD COLUMN IF NOT EXISTS net_total DECIMAL(12,3) DEFAULT 0 AFTER discount_amount;
+
+-- Add tax_category for classification
+-- standard = 16%, zero_rated = 0%, exempt = no tax, special = variable rate
+ALTER TABLE invoice_lines
+  ADD COLUMN IF NOT EXISTS tax_category VARCHAR(20) DEFAULT 'standard' AFTER net_total;
+
+-- Backfill existing data: calculate tax_amount from line_total * tax_rate
+UPDATE invoice_lines
+SET tax_amount = ROUND(line_total * tax_rate, 3)
+WHERE tax_amount = 0 AND line_total > 0;
+
+-- Backfill: net_total = line_total + tax_amount - discount
+UPDATE invoice_lines
+SET net_total = ROUND(line_total + tax_amount - discount_amount, 3)
+WHERE net_total = 0 AND line_total > 0;
+
+-- Classify zero-rated items
+UPDATE invoice_lines
+SET tax_category = 'zero_rated'
+WHERE tax_rate = 0 OR tax_rate IS NULL;
+
+-- Classify standard rate items
+UPDATE invoice_lines
+SET tax_category = 'standard'
+WHERE tax_rate = 0.16;