Create the income and asset tables.

lib/db.dart

@@ -24,8 +24,9 @@ class DatabaseHelper {
     String path = join(documentsDirectory.path, "com_hyperling_expense.db");
     return await openDatabase(
       path,
-      version: 1,
+      version: 2,
       onCreate: _onCreate,
+      onUpgrade: _onUpgrade,
     );
   }
 
@@ -41,6 +42,29 @@ class DatabaseHelper {
       """);
   }
 
+  Future _onUpgrade(Database db, int previousVersion, int newVersion) async {
+    // Added in DB version 2.
+    if (previousVersion < 2 && newVersion >= 2) {
+      await db.execute("""
+        CREATE TABLE income
+          ( id INTEGER PRIMARY KEY
+          , name TEXT NOT NULL UNIQUE
+          , revenue DOUBLE NOT NULL
+          , frequency TEXT NOT NULL
+          , description TEXT
+        )
+        """);
+      await db.execute("""
+        CREATE TABLE asset
+          ( id INTEGER PRIMARY KEY
+          , name TEXT NOT NULL UNIQUE
+          , amount DOUBLE NOT NULL
+          , description TEXT
+        )
+        """);
+    }
+  }
+
   /// Expense Section
   ///
   Future<List<Expense>> getExpenses() async {
@@ -81,8 +105,11 @@ class DatabaseHelper {
 
   Future<bool> checkExpenseNameExists(String name) async {
     Database db = await instance.db;
-    var expenses = await db.query("expense",
+    var expenses = await db.query(
-        where: "name = ?", whereArgs: [name],);
+      "expense",
+      where: "name = ?",
+      whereArgs: [name],
+    );
     return expenses.isNotEmpty;
   }