diff --git a/lib/models/radkfile/radicals_search_result.dart b/lib/models/radkfile/radicals_search_result.dart
deleted file mode 100644
index 4f9d346..0000000
--- a/lib/models/radkfile/radicals_search_result.dart
+++ /dev/null
@@ -1,3 +0,0 @@
-class RadicalsSearchResult {
-  // TODO: implement me
-}
diff --git a/lib/search.dart b/lib/search.dart
index 5d4490f..aa8c2ae 100644
--- a/lib/search.dart
+++ b/lib/search.dart
@@ -1,6 +1,6 @@
 import 'package:jadb/models/word_search/word_search_result.dart';
 import 'package:jadb/models/kanji_search/kanji_search_result.dart';
-import 'package:jadb/models/radkfile/radicals_search_result.dart';
+import 'package:jadb/search/radical_search.dart';
 import 'package:jadb/search/word_search/word_search.dart';
 
 import 'package:jadb/search/kanji_search.dart';
@@ -15,15 +15,15 @@ class JaDBConnection {
   Future<KanjiSearchResult?> searchKanji(String kanji) =>
       searchKanjiWithDbConnection(this._connection, kanji);
 
-  Future<RadicalsSearchResult> searchKanjiByRadicals(
-    List<String> radicals,
-  ) async {
-    throw UnimplementedError();
-  }
-
   Future<List<WordSearchResult>?> searchWord(String word) =>
       searchWordWithDbConnection(this._connection, word);
 
   Future<int?> searchWordCount(String word) =>
       searchWordCountWithDbConnection(this._connection, word);
+
+  Future<List<String>> searchRemainingRadicals(List<String> radicals) =>
+      searchRemainingRadicalsWithDbConnection(this._connection, radicals);
+
+  Future<List<String>> searchKanjiByRadicals(List<String> radicals) =>
+      searchKanjiByRadicalsWithDbConnection(this._connection, radicals);
 }
diff --git a/lib/search/radical_search.dart b/lib/search/radical_search.dart
new file mode 100644
index 0000000..3a28a4a
--- /dev/null
+++ b/lib/search/radical_search.dart
@@ -0,0 +1,60 @@
+import 'package:sqflite_common/sqlite_api.dart';
+
+// TODO: validate that the list of radicals all are valid radicals
+
+/// Given a list of radicals, search which kanji contains all
+/// of the radicals, find their other radicals, and return those.
+/// This is used to figure out which remaining combinations of radicals
+/// the user can search for without getting zero results.
+Future<List<String>> searchRemainingRadicalsWithDbConnection(
+  DatabaseExecutor connection,
+  List<String> radicals,
+) async {
+  final queryResult = await connection.rawQuery(
+    '''
+      SELECT DISTINCT radical
+      FROM RADKFILE
+      WHERE kanji IN (
+        SELECT kanji
+        FROM RADKFILE
+        WHERE radical IN (${List.filled(radicals.length, '?').join(',')})
+        GROUP BY kanji
+        HAVING COUNT(DISTINCT radical) = ?
+      )
+    ''',
+    [
+      ...radicals,
+      radicals.length,
+    ],
+  );
+
+  final remainingRadicals =
+      queryResult.map((row) => row['radical'] as String).toList();
+
+  return remainingRadicals;
+}
+
+/// Given a list of radicals, search which kanji contains all
+/// of the radicals, and return those.
+Future<List<String>> searchKanjiByRadicalsWithDbConnection(
+  DatabaseExecutor connection,
+  List<String> radicals,
+) async {
+  final queryResult = await connection.rawQuery(
+    '''
+      SELECT kanji
+      FROM RADKFILE
+      WHERE radical IN (${List.filled(radicals.length, '?').join(',')})
+      GROUP BY kanji
+      HAVING COUNT(DISTINCT radical) = ?
+    ''',
+    [
+      ...radicals,
+      radicals.length,
+    ],
+  );
+
+  final kanji = queryResult.map((row) => row['kanji'] as String).toList();
+
+  return kanji;
+}