diff --git a/src/Jiaowu.Api/Controllers/UsersController.cs b/src/Jiaowu.Api/Controllers/UsersController.cs
index 83bedfb..fd54cc8 100644
--- a/src/Jiaowu.Api/Controllers/UsersController.cs
+++ b/src/Jiaowu.Api/Controllers/UsersController.cs
@@ -170,10 +170,10 @@ public sealed class UsersController(
             {
                 while (await reader.ReadAsync(cancellationToken))
                 {
-                    var id = Guid.Parse(reader.GetString(0));
+                    var id = reader.GetGuid(0);
                     users.Add(new UserListItem(id, reader.GetString(1), reader.GetString(2),
                         reader.IsDBNull(3) ? null : reader.GetString(3),
-                        reader.IsDBNull(4) ? null : Guid.Parse(reader.GetString(4)),
+                        reader.IsDBNull(4) ? null : reader.GetGuid(4),
                         Convert.ToBoolean(reader.GetValue(5)),
                         reader.IsDBNull(6) ? null : reader.GetDateTime(6),
                         reader.GetDateTime(7), Array.Empty<string>()));
@@ -188,11 +188,11 @@ public sealed class UsersController(
                     "JOIN `AspNetRoles` r ON ur.`RoleId` = r.`Id` WHERE ur.`UserId` IN (" +
                     string.Join(", ", users.Select((_, index) => "@user" + index)) + ")", connection);
                 foreach (var (user, index) in users.Select((user, index) => (user, index)))
-                    rolesCommand.Parameters.AddWithValue("@user" + index, user.Id.ToString());
+                    rolesCommand.Parameters.AddWithValue("@user" + index, user.Id);
                 await using var roleReader = await rolesCommand.ExecuteReaderAsync(cancellationToken);
                 while (await roleReader.ReadAsync(cancellationToken))
                 {
-                    var userId = Guid.Parse(roleReader.GetString(0));
+                    var userId = roleReader.GetGuid(0);
                     if (!rolesByUser.TryGetValue(userId, out var roles)) rolesByUser[userId] = roles = [];
                     roles.Add(roleReader.GetString(1));
                 }
@@ -216,7 +216,7 @@ public sealed class UsersController(
         var command = new MySqlCommand(sql, connection);
         if (!string.IsNullOrWhiteSpace(keyword)) command.Parameters.AddWithValue("@keyword", keyword.Trim());
         if (!string.IsNullOrWhiteSpace(roleName)) command.Parameters.AddWithValue("@roleName", roleName.Trim());
-        if (collegeId.HasValue) command.Parameters.AddWithValue("@collegeId", collegeId.Value.ToString());
+        if (collegeId.HasValue) command.Parameters.AddWithValue("@collegeId", collegeId.Value);
         if (isEnabled.HasValue) command.Parameters.AddWithValue("@isEnabled", isEnabled.Value);
         return command;
     }