BUG: broken datetime when using to_sql()

[teweihuang]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
import sqlite3

today = pd.to_datetime("2023/9/5")
ele = [1, 2, 3]
df = pd.DataFrame({'date': [today] * len(ele), 'data': ele})
df.set_index('date', inplace=True)

conn = sqlite3.connect('date.db')
df.to_sql('test_date', conn, if_exists='replace')
conn.close()

Issue Description

the date in db becoming like this : 1693843200

the same code was working properly in 2.0.3, the date was correctly identified into YYYY-mm-dd.

I understand it's suggested to use utc=True, but please don't just make db broken instantly, that hurts.

it would be appreciated if devs could take a look.

Expected Behavior

It should be identified as YYYY-mm-dd, in this case, 2023-09-05 00:00:00, when using .to_sql() saving in db.

Installed Versions

INSTALLED VERSIONS ------------------ commit : ba1cccd python : 3.11.5.final.0 python-bits : 64 OS : Windows OS-release : 10 Version : 10.0.22621 machine : AMD64 processor : AMD64 Family 23 Model 113 Stepping 0, AuthenticAMD byteorder : little LC_ALL : None LANG : None LOCALE : Chinese (Traditional)_Taiwan.950 pandas : 2.1.0 numpy : 1.25.2 pytz : 2023.3 dateutil : 2.8.2 setuptools : 68.1.2 pip : 23.2.1 Cython : None pytest : None hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : 4.9.3 html5lib : None pymysql : None psycopg2 : None jinja2 : None IPython : None pandas_datareader : None bs4 : 4.12.2 bottleneck : None dataframe-api-compat: None fastparquet : None fsspec : None gcsfs : None matplotlib : 3.7.2 numba : None numexpr : None odfpy : None openpyxl : None pandas_gbq : None pyarrow : None pyreadstat : None pyxlsb : None s3fs : None scipy : 1.11.2 sqlalchemy : None tables : None tabulate : None xarray : None xlrd : None zstandard : None tzdata : 2023.3 qtpy : None pyqt5 : None

[asishm]

Thanks for the report. Duplicate of #54877

[mroeschke]

Thanks for the report. This will be fixed in 2.1.1