问题
The documentation I've run across researching this indicates that the way to do it for other databases is to use multiple statements in your query, a la:
>>> cursor = connection.cursor()
>>> cursor.execute("set session transaction isolation level read uncommitted;
select stuff from table;
set session transaction isolation level repeatable read;")
Unfortunately, doing that yields no results, as apparently the Python DB API (or maybe just this implementation of it?) doesn't support multiple recordsets within a single query.
Has anyone else had success with this in the past?
回答1:
I don't think this works for the MySQLdb driver; you'll have to issue separate queries:
cur = conn.cursor()
cur.execute("SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED")
cur.execute("SELECT @@session.tx_isolation")
print cur.fetchall()[0]
cur.execute("SELECT * FROM bar")
print cur.fetchall()
cur.execute("SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ")
cur.execute("SELECT @@session.tx_isolation")
print cur.fetchall()[0]
# output
('READ-UNCOMMITTED',)
(('foo',), ('bar',))
('REPEATABLE-READ',)
The MySQLdb cursor's execute() method only sees the first query up to the semicolon:
cur.execute("SELECT * FROM bar WHERE thing = 'bar'; SELECT * FROM bar")
print cur.fetchall()
# output
(('bar',),)
来源:https://stackoverflow.com/questions/5677379/how-do-you-change-the-sql-isolation-level-from-python-using-mysqldb