diff --git a/tinydb/table.py b/tinydb/table.py
index c562d02f..6b41a342 100644
--- a/tinydb/table.py
+++ b/tinydb/table.py
@@ -383,131 +383,46 @@ def update(
         :returns: a list containing the updated document's ID
         """
 
-        # Define the function that will perform the update
-        if callable(fields):
-            def perform_update(table, doc_id):
-                # Update documents by calling the update function provided by
-                # the user
-                fields(table[doc_id])
-        else:
-            def perform_update(table, doc_id):
-                # Update documents by setting all fields from the provided data
-                table[doc_id].update(fields)
-
-        if doc_ids is not None:
-            # Perform the update operation for documents specified by a list
-            # of document IDs
-
-            updated_ids = list(doc_ids)
-
-            def updater(table: dict):
-                # Call the processing callback with all document IDs
-                for doc_id in updated_ids:
-                    perform_update(table, doc_id)
-
-            # Perform the update operation (see _update_table for details)
-            self._update_table(updater)
-
-            return updated_ids
-
-        elif cond is not None:
-            # Perform the update operation for documents specified by a query
+        # Define the function to perform the update based on `fields`
+        def perform_update(table, doc_id):
+            if callable(fields):
+                fields(table[doc_id])  # Call user-defined function
+            else:
+                table[doc_id].update(fields)  # Update with provided fields
 
-            # Collect affected doc_ids
+        # Helper to process document IDs
+        def process_doc_ids(table, ids):
             updated_ids = []
-
-            def updater(table: dict):
-                _cond = cast(QueryLike, cond)
-
-                # We need to convert the keys iterator to a list because
-                # we may remove entries from the ``table`` dict during
-                # iteration and doing this without the list conversion would
-                # result in an exception (RuntimeError: dictionary changed size
-                # during iteration)
-                for doc_id in list(table.keys()):
-                    # Pass through all documents to find documents matching the
-                    # query. Call the processing callback with the document ID
-                    if _cond(table[doc_id]):
-                        # Add ID to list of updated documents
-                        updated_ids.append(doc_id)
-
-                        # Perform the update (see above)
-                        perform_update(table, doc_id)
-
-            # Perform the update operation (see _update_table for details)
-            self._update_table(updater)
-
+            for doc_id in ids:
+                updated_ids.append(doc_id)
+                perform_update(table, doc_id)
             return updated_ids
 
-        else:
-            # Update all documents unconditionally
-
+        # Update based on conditions
+        def process_condition(table, condition):
             updated_ids = []
-
-            def updater(table: dict):
-                # Process all documents
-                for doc_id in list(table.keys()):
-                    # Add ID to list of updated documents
+            for doc_id, doc in list(table.items()):
+                if condition(doc):
                     updated_ids.append(doc_id)
-
-                    # Perform the update (see above)
                     perform_update(table, doc_id)
-
-            # Perform the update operation (see _update_table for details)
-            self._update_table(updater)
-
             return updated_ids
 
-    def update_multiple(
-        self,
-        updates: Iterable[
-            Tuple[Union[Mapping, Callable[[Mapping], None]], QueryLike]
-        ],
-    ) -> List[int]:
-        """
-        Update all matching documents to have a given set of fields.
-
-        :returns: a list containing the updated document's ID
-        """
-
-        # Define the function that will perform the update
-        def perform_update(fields, table, doc_id):
-            if callable(fields):
-                # Update documents by calling the update function provided
-                # by the user
-                fields(table[doc_id])
-            else:
-                # Update documents by setting all fields from the provided
-                # data
-                table[doc_id].update(fields)
+        # Select the appropriate update logic
+        def update_logic(table):
+            if doc_ids is not None:
+                return process_doc_ids(table, doc_ids)
+            if cond is not None:
+                return process_condition(table, cond)
+            # Update all documents if no condition or IDs provided
+            return process_doc_ids(table, list(table.keys()))
 
-        # Perform the update operation for documents specified by a query
-
-        # Collect affected doc_ids
+        # Perform the update operation (see `_update_table` for details)
         updated_ids = []
+        def updater(table):
+            nonlocal updated_ids
+            updated_ids = update_logic(table)
 
-        def updater(table: dict):
-            # We need to convert the keys iterator to a list because
-            # we may remove entries from the ``table`` dict during
-            # iteration and doing this without the list conversion would
-            # result in an exception (RuntimeError: dictionary changed size
-            # during iteration)
-            for doc_id in list(table.keys()):
-                for fields, cond in updates:
-                    _cond = cast(QueryLike, cond)
-
-                    # Pass through all documents to find documents matching the
-                    # query. Call the processing callback with the document ID
-                    if _cond(table[doc_id]):
-                        # Add ID to list of updated documents
-                        updated_ids.append(doc_id)
-
-                        # Perform the update (see above)
-                        perform_update(fields, table, doc_id)
-
-        # Perform the update operation (see _update_table for details)
         self._update_table(updater)
-
         return updated_ids
 
     def upsert(self, document: Mapping, cond: Optional[QueryLike] = None) -> List[int]: