diff --git a/resources/sql/003_normalize_timestamp_columns.sql b/resources/sql/003_normalize_timestamp_columns.sql
index bd99af4..c4a13b9 100644
--- a/resources/sql/003_normalize_timestamp_columns.sql
+++ b/resources/sql/003_normalize_timestamp_columns.sql
@@ -44,20 +44,4 @@ BEGIN
                  ALTER COLUMN timestamp TYPE TIMESTAMP WITH TIME ZONE
                  USING "timestamp" AT TIME ZONE ''UTC''';
     END IF;
-
-    IF EXISTS (
-        SELECT 1
-        FROM information_schema.columns
-        WHERE table_schema = 'public'
-          AND table_name = 'scheme_list'
-          AND column_name = 'scheme_start_time'
-          AND data_type IN ('character varying', 'text')
-    ) THEN
-        EXECUTE 'ALTER TABLE public.scheme_list
-                 ALTER COLUMN scheme_start_time TYPE TIMESTAMP WITH TIME ZONE
-                 USING CASE
-                     WHEN scheme_start_time ~ ''(Z|[+-][0-9]{2}:[0-9]{2})$'' THEN scheme_start_time::timestamptz
-                     ELSE scheme_start_time::timestamp AT TIME ZONE ''UTC''
-                 END';
-    END IF;
 END $$;
diff --git a/resources/sql/create/40.scheme_list.sql b/resources/sql/create/40.scheme_list.sql
index 7d5ea3a..5563403 100644
--- a/resources/sql/create/40.scheme_list.sql
+++ b/resources/sql/create/40.scheme_list.sql
@@ -9,6 +9,6 @@ create table scheme_list (
     scheme_type varchar(32) not null,
     username varchar(32) not null,
     create_time TIMESTAMP WITH TIME ZONE not null DEFAULT date_trunc('minute', CURRENT_TIMESTAMP),
-    scheme_start_time TIMESTAMP WITH TIME ZONE not null,
+    scheme_start_time varchar(50) not null,
     scheme_detail JSON
 )