added function to insert data

database.py

@@ -147,4 +147,13 @@ class Data_table(Table):
             'ON CONFLICT (username, time, content) DO NOTHING '
             ';'
         )
-        self.execute(query, val_dict)
+        self.execute(query, val_dict)
+
+def insert(username, timestamp, content):
+    val_dict = {
+        'username': username,
+        'time': timestamp,
+        'content': content
+    }
+    with Data_table() as dt:
+        dt.insert(val_dict)