Update app.py

app.py

@@ -14,7 +14,7 @@ def app():
     st.title("Pizza Sales Data Analysis Dashboard")
     df = load_data()
     
-    total_orders = df['order_id'].value_counts()    #function which can calculate the number of unique values
+    total_orders = df['order_id'].nunique()    #function which can calculate the number of unique values
     total_revenue = df['total_price'].sum()  #function which can sum the column
     most_popular_size = df['pizza_size'].value_counts().idxmax()    #function which can get the maximum value 
     most_frequent_category = df['pizza_category'].value_counts().idxmax()    #function which can count of value of each product