On 10 Ιαν, 03:11, Ian Kelly <ian.g.ke...@gmail.com> wrote: > 2012/1/9 Íéêüëáïò Êïýñáò <nikos.kou...@gmail.com>: > > > if the MySQL query was: > > > cursor.execute( '''SELECT host, hits, agent, date FROM visitors WHERE pin = > > %s ORDER BY date DESC''', pin ) > > > can you help me imagine how the mysql database cursor that holds the query > > results would look like? I must somehow visualize it in order to understand > > it! > > You can think of it as a pointer, traversing over one row of the > result set at a time. Hopefully this will come out legibly: > > ----------------------------------------------- > | HOST | HITS | AGENT | DATE | > ----------------------------------------------- ------------- > | foo | 7 | IE6 | 1/1/11 | <---- | cursor | > ----------------------------------------------- ------------- > | bar | 42 | Firefox | 2/2/10 | > ----------------------------------------------- > | baz | 4 | Chrome | 3/3/09 | > ------------------------------------------------
Database cursor is the pointer that iterates over the result set one row at a time? I though that it was the name we give to the whole mysql result set returned my cursor.execute. > > > > Also what happend if the query was: > > cursor.execute( '''SELECT host FROM visitors") ? > > > the result would have to be something likelike? > > > ----------------- > > |somehost1| > > ----------------- > > |somehost2| > > ----------------- > > |somehost3| > > ----------------- > > ..................... > > ..................... > > |somehost n| > > ----------------- > > > So what values host, hits, agent, date would have in 'for host, hits, agent, > > date in > > dataset' ? Every row has one string how can that be split in 4? > > Why don't you try it and see what happens? But to spare you the > suspense, you would get: > > ValueError: need more than 1 value to unpack > > Because you can't unpack a 1-length tuple into four variables. The > code assumes that the query is selecting exactly 4 columns. ----------------------------------------------- | HOST | HITS | AGENT | DATE | ----------------------------------------------- | foo | 7 | IE6 | 1/1/11 | ----------------------------------------------- | bar | 42 | Firefox | 2/2/10 | ----------------------------------------------- | baz | 4 | Chrome | 3/3/09 | ----------------------------------------------- In this line: for host, hits, agent, date in dataset: 'dataset' is one of the rows of the mysql result or the whole mysql result set like the table above? I still have trouble understanding this line :( -- http://mail.python.org/mailman/listinfo/python-list
