diff --git a/src/order_bak/csv_utils.py b/src/order_bak/csv_utils.py
new file mode 100644
index 0000000..7a079d7
--- /dev/null
+++ b/src/order_bak/csv_utils.py
@@ -0,0 +1,70 @@
+import csv
+from datetime import datetime
+from pathlib import Path
+from typing import Any
+
+CSV_COLUMNS = [
+    "PartitionKey",
+    "RowKey",
+    "OrderTime",
+    "ReceiveTime",
+    "revenue",
+    "platformOrder",
+    "prodCount",
+    "pfId",
+    "prodId",
+    "prodPrice",
+    "state",
+    "ver",
+    "customData",
+]
+
+
+def _format_value(val: Any) -> str:
+    if val is None:
+        return ""
+    if isinstance(val, datetime):
+        return val.isoformat()
+    return str(val)
+
+
+def entity_to_row(entity: dict[str, Any]) -> dict[str, str]:
+    return {col: _format_value(entity.get(col)) for col in CSV_COLUMNS}
+
+
+def _parse_row(raw: dict[str, str]) -> dict[str, Any]:
+    result: dict[str, Any] = {}
+    for col in CSV_COLUMNS:
+        val = raw.get(col, "")
+        if val == "":
+            result[col] = None
+            continue
+        if col in ("OrderTime", "ReceiveTime"):
+            result[col] = datetime.fromisoformat(val)
+        elif col in ("revenue", "prodPrice"):
+            result[col] = float(val)
+        elif col in ("prodCount", "state", "ver"):
+            result[col] = int(val)
+        else:
+            result[col] = val
+    return result
+
+
+def row_to_entity(raw: dict[str, str]) -> dict[str, Any]:
+    return _parse_row(raw)
+
+
+def write_csv(path: Path, entities: list[dict[str, Any]]) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    with open(path, "w", newline="") as f:
+        writer = csv.DictWriter(f, fieldnames=CSV_COLUMNS)
+        writer.writeheader()
+        for entity in entities:
+            writer.writerow(entity_to_row(entity))
+
+
+def read_csv(path: Path):
+    with open(path, newline="") as f:
+        reader = csv.DictReader(f)
+        for row in reader:
+            yield _parse_row(row)
diff --git a/tests/test_csv_utils.py b/tests/test_csv_utils.py
new file mode 100644
index 0000000..0c8c860
--- /dev/null
+++ b/tests/test_csv_utils.py
@@ -0,0 +1,132 @@
+import csv
+from datetime import datetime, timezone
+from pathlib import Path
+
+from order_bak.csv_utils import (
+    CSV_COLUMNS,
+    entity_to_row,
+    row_to_entity,
+    write_csv,
+    read_csv,
+)
+
+
+def test_csv_columns_defined():
+    assert "PartitionKey" in CSV_COLUMNS
+    assert "RowKey" in CSV_COLUMNS
+    assert "OrderTime" in CSV_COLUMNS
+    assert "state" in CSV_COLUMNS
+    assert len(CSV_COLUMNS) == 13
+
+
+def test_entity_to_row_converts_datetime():
+    entity = {
+        "PartitionKey": "user1",
+        "RowKey": "order1",
+        "OrderTime": datetime(2025, 6, 15, 10, 30, 0, tzinfo=timezone.utc),
+        "ReceiveTime": datetime(2025, 6, 15, 11, 0, 0, tzinfo=timezone.utc),
+        "revenue": 99.5,
+        "platformOrder": "plat123",
+        "prodCount": 2,
+        "pfId": "user1",
+        "prodId": "prod1",
+        "prodPrice": 49.75,
+        "state": 1,
+        "ver": 3,
+        "customData": '{"key":"val"}',
+    }
+    row = entity_to_row(entity)
+    assert row["OrderTime"] == "2025-06-15T10:30:00+00:00"
+    assert row["ReceiveTime"] == "2025-06-15T11:00:00+00:00"
+    assert row["revenue"] == "99.5"
+    assert row["state"] == "1"
+
+
+def test_entity_to_row_handles_none():
+    entity = {
+        "PartitionKey": "user1",
+        "RowKey": "order1",
+        "OrderTime": datetime(2025, 1, 1, tzinfo=timezone.utc),
+        "ReceiveTime": None,
+        "revenue": None,
+        "platformOrder": None,
+        "prodCount": None,
+        "pfId": None,
+        "prodId": None,
+        "prodPrice": None,
+        "state": 0,
+        "ver": None,
+        "customData": None,
+    }
+    row = entity_to_row(entity)
+    assert row["ReceiveTime"] == ""
+    assert row["revenue"] == ""
+
+
+def test_row_to_entity_roundtrip(tmp_path):
+    original = {
+        "PartitionKey": "user1",
+        "RowKey": "order1",
+        "OrderTime": "2025-06-15T10:30:00+00:00",
+        "ReceiveTime": "",
+        "revenue": "99.5",
+        "platformOrder": "plat123",
+        "prodCount": "2",
+        "pfId": "user1",
+        "prodId": "prod1",
+        "prodPrice": "49.75",
+        "state": "1",
+        "ver": "3",
+        "customData": '{"key":"val"}',
+    }
+    entity = row_to_entity(original)
+    assert entity["PartitionKey"] == "user1"
+    assert entity["state"] == 1
+    assert entity["revenue"] == 99.5
+    assert entity["prodCount"] == 2
+    assert entity["ReceiveTime"] is None
+
+
+def test_write_and_read_csv(tmp_path):
+    entities = [
+        {
+            "PartitionKey": "user1",
+            "RowKey": "order1",
+            "OrderTime": datetime(2025, 6, 15, 10, 30, tzinfo=timezone.utc),
+            "ReceiveTime": None,
+            "revenue": 99.5,
+            "platformOrder": "p1",
+            "prodCount": 2,
+            "pfId": "user1",
+            "prodId": "prod1",
+            "prodPrice": 49.75,
+            "state": 1,
+            "ver": 3,
+            "customData": None,
+        },
+        {
+            "PartitionKey": "user2",
+            "RowKey": "order2",
+            "OrderTime": datetime(2025, 6, 16, 12, 0, tzinfo=timezone.utc),
+            "ReceiveTime": datetime(2025, 6, 16, 13, 0, tzinfo=timezone.utc),
+            "revenue": 10.0,
+            "platformOrder": "p2",
+            "prodCount": 1,
+            "pfId": "user2",
+            "prodId": "prod2",
+            "prodPrice": 10.0,
+            "state": 1,
+            "ver": 3,
+            "customData": '{"note":"test"}',
+        },
+    ]
+    csv_path = tmp_path / "test.csv"
+    write_csv(csv_path, entities)
+
+    result = list(read_csv(csv_path))
+    assert len(result) == 2
+    assert result[0]["PartitionKey"] == "user1"
+    assert result[1]["PartitionKey"] == "user2"
+    assert result[1]["revenue"] == 10.0
+    assert result[0]["ReceiveTime"] is None
+    assert result[1]["ReceiveTime"] is not None