问题
When I try to run statements like:
cursor.executemany("""INSERT INTO `test` (`id`,`data`,`time_added`)
VALUES (%s, %s, NOW())""", [(i.id, i.data) for i in items])
MySQLdb seems to choke on the ) in NOW(), when it expands the list of rows to be inserted because it sees that parenthesis as the end of the value block. That is, the queries look like:
('1', 'a', NOW(), ('2','b', NOW(), ('3','c',NOW())
And MYSQL reports a syntax error. Instead, they should look like:
('1', 'a', NOW()), ('2','b', NOW()), ('3','c',NOW())
There should be some way to escape the NOW(), but I can't figure out how. Adding 'NOW()' to the tuple doesn't work because then NOW() is quoted and interpreted by the DB as a string rather than a function call.
Working around this by using current timestamp as default value is not an option -- this is an example, I need to do this sort of thing with a variety of db functions, not just now.
Thanks!
回答1:
The method below is far from ideal, but, unfortunately, it is the only way I know.
The idea is to manually construct the SQL, using connection.literal
to escape the arguments for you:
cursor=connection.cursor()
args=[(1,'foo'),(2,'bar')]
sql=('INSERT INTO `foo` (`fooid`,`data`,`time_added`) VALUES '
+','.join(
['(%s,%s,NOW())'%connection.literal(arg)
for arg in args]))
cursor.execute(sql)
This looks horrible, and may make your skin crawl, but if you look under the hood (in /usr/lib/pymodules/python2.6/MySQLdb/cursors.py) at what MySQLdb is doing in cursors.executemany
, I think this is along the same lines as what that function is doing, minus the mixup due the regex cursors.insert_values
not correctly parsing the nested parentheses. (eek!)
I've just installed oursql, an alternative to MySQLdb, and am happy to report that
sql='INSERT INTO `foo` (`fooid`,`data`,`time_added`) VALUES (?,?,NOW())'
cursor.executemany(sql,args)
works as expected with oursql.
来源:https://stackoverflow.com/questions/4879606/including-db-function-calls-in-python-mysqldb-executemany