@Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        // Create a table to hold locations.  A location consists of the string supplied in the
        // location setting, the city name, and the latitude and longitude
        final String SQL_CREATE_LOCATION_TABLE = "CREATE TABLE " + LocationEntry.TABLE_NAME + " (" +
                LocationEntry._ID + " INTEGER PRIMARY KEY," +
                LocationEntry.COLUMN_LOCATION_SETTING + " TEXT UNIQUE NOT NULL, " +
                LocationEntry.COLUMN_CITY_NAME + " TEXT NOT NULL, " +
                LocationEntry.COLUMN_COORD_LAT + " REAL NOT NULL, " +
                LocationEntry.COLUMN_COORD_LONG + " REAL NOT NULL " +
                " );";

        final String SQL_CREATE_WEATHER_TABLE = "CREATE TABLE " + WeatherEntry.TABLE_NAME + " (" +
                // Why AutoIncrement here, and not above?
                // Unique keys will be auto-generated in either case.  But for weather
                // forecasting, it's reasonable to assume the user will want information
                // for a certain date and all dates *following*, so the forecast data
                // should be sorted accordingly.
                WeatherEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +

                // the ID of the location entry associated with this weather data
                WeatherEntry.COLUMN_LOC_KEY + " INTEGER NOT NULL, " +
                WeatherEntry.COLUMN_DATE + " INTEGER NOT NULL, " +
                WeatherEntry.COLUMN_SHORT_DESC + " TEXT NOT NULL, " +
                WeatherEntry.COLUMN_WEATHER_ID + " INTEGER NOT NULL," +

                WeatherEntry.COLUMN_MIN_TEMP + " REAL NOT NULL, " +
                WeatherEntry.COLUMN_MAX_TEMP + " REAL NOT NULL, " +

                WeatherEntry.COLUMN_HUMIDITY + " REAL NOT NULL, " +
                WeatherEntry.COLUMN_PRESSURE + " REAL NOT NULL, " +
                WeatherEntry.COLUMN_WIND_SPEED + " REAL NOT NULL, " +
                WeatherEntry.COLUMN_DEGREES + " REAL NOT NULL, " +

                // Set up the location column as a foreign key to location table.
                " FOREIGN KEY (" + WeatherEntry.COLUMN_LOC_KEY + ") REFERENCES " +
                LocationEntry.TABLE_NAME + " (" + LocationEntry._ID + "), " +

                // To assure the application have just one weather entry per day
                // per location, it's created a UNIQUE constraint with REPLACE strategy
                " UNIQUE (" + WeatherEntry.COLUMN_DATE + ", " +
                WeatherEntry.COLUMN_LOC_KEY + ") ON CONFLICT REPLACE);";

        sqLiteDatabase.execSQL(SQL_CREATE_LOCATION_TABLE);
        sqLiteDatabase.execSQL(SQL_CREATE_WEATHER_TABLE);
    }
Manages a local database for weather data.
app/src/main/java/com/example/android/sunshine/app/data/WeatherDbHelper.java