How do you change the SQL isolation level from Python using MySQLdb?

Question

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:

&g         


        

Answer 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',),)

Answer 2

cur.executemany("SELECT * FROM bar WHERE thing = 'bar'; SELECT * FROM bar")
print cur.fetchall()

use cur.executemany to run multiple sql statements with ; separated.