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I just started using sqlite3 with python . I would like to know the difference between :
cursor = db.execute("SELECT customer FROM table")
for row in cursor:
print row[0]
and
cursor = db.execute("SELECT customer FROM table")
for row in cursor.fetchall():
print row[0]
Except that cursor is <type 'sqlite3.Cursor'> and cursor.fetchall() is <type 'list'>, both of them have the same result .
Is there a difference, a preference or specific cases where one is more preferred than the other ?
256
The sqlite3. Cursor class provides three methods namely fetchall(), fetchmany() and, fetchone() where, The fetchall() method retrieves all the rows in the result set of a query and returns them as list of tuples. (If we execute this after retrieving few rows it returns the remaining ones).
fetchall() Method. The method fetches all (or all remaining) rows of a query result set and returns a list of tuples. If no more rows are available, it returns an empty list. You must fetch all rows for the current query before executing new statements using the same connection.
fetchall() fetches all the rows of a query result. It returns all the rows as a list of tuples. An empty list is returned if there is no record to fetch. cursor.
The sqlite3. Cursor class is an instance using which you can invoke methods that execute SQLite statements, fetch data from the result sets of the queries. You can create Cursor object using the cursor() method of the Connection object/class.
fetchall() reads all records into memory, and then returns that list.
When iterating over the cursor itself, rows are read only when needed. This is more efficient when you have much data and can handle the rows one by one.
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