我想使用 connection.execute
插入多行,其中一列必须设置为数据库的 CURRENT_TIMESTAMP
函数的结果。
例如,给定这张表:
import sqlalchemy as sa
metadata = sa.MetaData()
foo = sa.Table('foo', metadata,
sa.Column('id', sa.Integer, primary_key=True),
sa.Column('ts', sa.TIMESTAMP))
# I'm using Sqlite for this example, but this question
# is database-agnostic.
engine = sa.create_engine('sqlite://', echo=True)
metadata.create_all(engine)
我可以像这样插入一行:
conn = engine.connect()
with conn.begin():
ins = foo.insert().values(ts=sa.func.current_timestamp())
conn.execute(ins)
但是当我尝试插入多行时:
with conn.begin():
ins = foo.insert()
conn.execute(ins, [{'ts': sa.func.current_timestamp()}])
引发了一个TypeError
:
sqlalchemy.exc.StatementError: (builtins.TypeError) SQLite DateTime type only accepts Python datetime and date objects as input.
[SQL: INSERT INTO foo (ts) VALUES (?)]
[parameters: [{'ts': <sqlalchemy.sql.functions.current_timestamp at 0x7f3607e21070; current_timestamp>}]
用字符串“CURRENT_TIMESTAMP”替换函数会导致类似的错误。
有没有办法让数据库使用 connection.execute
将列设置为 CURRENT_TIMESTAMP
?
我知道我可以通过在同一事务中查询 CURRENT_TIMESTAMP
的值并在 INSERT
值中使用该值,或执行和UPDATE
在 INSERT
之后。我特别想问这是否可以在 connection.execute
的 *multiparams
参数中完成。
最佳答案
这当然是一个 hack,但这似乎至少适用于 SQLite:
from datetime import datetime
from pprint import pprint
import sqlalchemy as sa
engine = sa.create_engine("sqlite:///:memory:")
metadata = sa.MetaData()
foo = sa.Table(
"foo",
metadata,
sa.Column("id", sa.Integer, primary_key=True, autoincrement=True),
sa.Column("ts", sa.TIMESTAMP),
sa.Column("txt", sa.String(50)),
)
foo.create(engine)
with engine.begin() as conn:
ins_query = str(foo.insert().compile()).replace(
" :ts, ", " CURRENT_TIMESTAMP, "
)
print(ins_query)
# INSERT INTO foo (id, ts, txt) VALUES (:id, CURRENT_TIMESTAMP, :txt)
data = [{"id": None, "txt": "Alfa"}, {"id": None, "txt": "Bravo"}]
conn.execute(sa.text(ins_query), data)
print(datetime.now())
# 2021-03-06 17:41:35.743452
# (local time here is UTC-07:00)
results = conn.execute(sa.text("SELECT * FROM foo")).fetchall()
pprint(results, width=60)
"""
[(1, '2021-03-07 00:41:35', 'Alfa'),
(2, '2021-03-07 00:41:35', 'Bravo')]
"""
关于python - 如何使用 SQLAlchemy 的 connection.execute 插入 CURRENT TIMESTAMP 的值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/66508799/