Imagine I have a mysql cursor and data read. The amount of data might be very big that I want to deal with one line each time.
An easy and straight forward way might be like this:
while True: row = cursor.fetchone() if not row: break .....
But this doesn’t look good, so I wonder whether this way works as imagined:
for row in iter(cursor.fetchall())
The thing I want to know is: if I use the iter(cursor.fetchall())
way, does it fetch all the data first or it just fetch one row at a time?
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Answer
The MySQLdb
cursor class implements the iterator protocol, so you can simply do this:
cursor.execute(sql) for row in cursor: print row ...
Relevant code from MySQLdb.cursors.BaseCursor:
def __iter__(self): return iter(self.fetchone, None)