在SQLAlchemy Core中执行多个独立语句？

Question

I'm using SQLAlchemy Core to run a few independent statements. The statements are to separate tables and unrelated . Because of that I can't use the standard table.insert() with multiple dictionaries of params passed in. Right now, I'm doing this:

sql_conn.execute(query1)
sql_conn.execute(query2)

Is there any way I can run these in one shot instead of needing two back-and-forths to the db? I'm on MySQL 5.7 and Python 2.7.11.

Answer 1

It is neither wise, nor practical, to run two queries at once.

It is not wise allowing such give hackers another way to do nasty things via "SQL Injection".

On the other hand, it is possible, but not necessarily practical. You would create a Stored Procedure that contains any number of related (or unrelated) queries in it. Then CALL that procedure. There some things that may make it impractical:

• The only way to get data in is via a finite number of scalar arguments.
• The output comes back as multiple resultsets; you need to code differently to see what happened.

Roundtrip latency is insignificant if you are on the same machine with the MySQL server. It can usually be ignored even if the two servers are in the same datacenter. Latency becomes important when the client and server are separated by a long distance. For cross-Atlantic latency, we are talking over 100ms. Brazil to China is about 250ms. (Be glad we are no living on Jupiter.)

Answer 2

Sounds like you want a Transaction :

with engine.connect() as sql_conn:
    with sql_conn.begin():
        sql_conn.execute(query1)
        sql_conn.execute(query2)

There is an implicit sql_conn.commit() above (when using the context manager) which commits the changes to the database in one trip. If you want to do it explicitly, it's done like this:

from sqlalchemy import create_engine
engine = create_engine("postgresql://scott:tiger@localhost/test")
connection = engine.connect()
trans = connection.begin()
connection.execute(text("insert into x (a, b) values (1, 2)"))
trans.commit()

https://docs.sqlalchemy.org/en/14/core/connections.html#basic-usage