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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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MySQL cursor is a kind of loop facility given to traverse in the result of SQL one by one. We can operate on every result by using the cursor in MySQL. Cursors are supported in stored procedures, functions, and triggers only. MySQL cursor is available from version 5 or greater.
MySQL supports cursors inside stored programs. The syntax is as in embedded SQL.
Initially cursor is not on the first row show using moveToNext() you can iterate the cursor when record is not exist then it return false ,unless it return true , while (cursor. moveToNext()) { ... }
They help you execute a specific sequence of instructions repeatedly until a particular condition breaks the loop. MySQL also provides a way to execute instructions on individual rows using cursors. Cursors in MySQL will execute a set of instructions on rows returned from SQL queries.
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) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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