better trade endpoints

internal/database/main.go

@@ -19,7 +19,7 @@ func InitDB(db *sql.DB) {
     CREATE TABLE IF NOT EXISTS trades (
         id          INTEGER PRIMARY KEY AUTOINCREMENT,
         company_id  INTEGER NOT NULL,
-        currency_id INTEGER NOT NULL,
+        currency_code TEXT NOT NULL,
         shares      INTEGER NOT NULL,
         product     INTEGER NOT NULL CHECK(product IN (0, 1, 2, 3)),
         type        INTEGER NOT NULL CHECK(type IN (0, 1)),
@@ -118,3 +118,34 @@ func MigrateAddUniqueToRevenueEntries(db *sql.DB) error {
 	}
 	return nil
 }
+
+func MigrateTradeCode(db *sql.DB) error {
+	step :=
+		// 1. copy existing data into a temp table with the new constraint
+		`
+        ALTER TABLE trades RENAME TO trades_old;
+
+CREATE TABLE IF NOT EXISTS trades (
+    id            INTEGER PRIMARY KEY AUTOINCREMENT,
+    company_id    INTEGER NOT NULL,
+    currency_code TEXT NOT NULL,
+    shares        INTEGER NOT NULL,
+    product       INTEGER NOT NULL CHECK(product IN (0, 1, 2, 3)),
+    type          INTEGER NOT NULL CHECK(type IN (0, 1)),
+    price         REAL    NOT NULL,
+    traded_at     DATETIME NOT NULL
+);
+
+INSERT INTO trades (id, company_id, currency_code, shares, product, type, price, traded_at)
+SELECT id, company_id, '', shares, product, type, price, traded_at
+FROM trades_old;
+
+DROP TABLE trades_old;
+    `
+
+	_, err := db.Exec(step)
+	if err != nil {
+		return fmt.Errorf("migration failed: %w", err)
+	}
+	return nil
+}