diff --git a/database-tutorial/docs.md b/database-tutorial/docs.md
index 36ff7d1..5584964 100644
--- a/database-tutorial/docs.md
+++ b/database-tutorial/docs.md
@@ -695,7 +695,7 @@ const insertResult = await mySqlClient.execute(`
     INSERT INTO teacher_自分の名前 (
         name, joining_date
     ) VALUES (
-        ??, ??
+        ?, ?
     );
 `, [
     "じぐ美先生",