BUG: Pandas 2.2 breaks SQLAlchemy 1.4 compatibility

[miraculixx]

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Reproducible Example

# with SQL Alchemy 1.4 installed the following example fails:
import pandas as pd
from sqlalchemy import create_engine
con = create_engine('sqlite:///:memory:')
df = pd.DataFrame({'a': [0, 1, 2, 3]})
df.to_sql('test', con)
=> AttributeError: 'Engine' object has no attribute 'cursor'

Issue Description

While Pandas 2.2 Release Notes declare sqlalchemy > 2.0.0 a minimum requirement, sqlalchemy 1.4 is still a widely used and maintained release. This change thus likely breaks a lot of existing code. Upgrading from sqlalchemy 1.4 to 2.0 is not trivial and therefore many projects using both pandas and sqlalchemy will not be able to upgrade to pandas > 2.2 easily.

Expected Behavior

SQLAlchemy 1.4 compatibility should be continued, and 1.4 support should be deprecated before removal.

Installed Versions

sphinx : 7.2.6
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.3
IPython : 8.20.0
pandas_datareader : None
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.12.3
bottleneck : None
dataframe-api-compat : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
python-calamine : None
pyxlsb : None
s3fs : None
scipy : 1.11.4
sqlalchemy : None
tables : None
tabulate : 0.9.0
xarray : None
xlrd : None
zstandard : None
tzdata : 2023.4
qtpy : None
pyqt5 : None

[miraculixx]

Further testing indicates the compatibility issue may only apply to SQLite. For example for MySQL + sqlalchemy 1.4 this still works:

import pandas as pd
from sqlalchemy import create_engine
con = create_engine('mysql+pymysql://root:password@localhost:3306/test')
df = pd.DataFrame({'a': [0, 1, 2, 3]})
df.to_sql('test', con, if_exists='replace')

Running mysql using docker docker run --name=mysql -e MYSQL_ROOT_PASSWORD=password -p 3306:3306 mysql

[lithomas1]

While Pandas 2.2 Release Notes declare sqlalchemy > 2.0.0 a minimum requirement, sqlalchemy 1.4 is still a widely used and maintained release. This change thus likely breaks a lot of existing code. Upgrading from sqlalchemy 1.4 to 2.0 is not trivial and therefore many projects using both pandas and sqlalchemy will not be able to upgrade to pandas > 2.2 easily.

This seems reasonable to me, since it looks like sqlalchemy 1.4 is still getting releases, so it'd probably make sense to support it at least until sqlalchemy 2.1 comes out.

Usually, we bump minimum versions of dependencies once they become around 2 years old (and sqlalchemy 1.4 is already 3 years old), but I think was it's probably fine to make an exception for sqlalchemy this time.

cc @mroeschke