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I am confused about why python needs cursor object. I know jdbc and there the database connection is quite intuitive but in python I am confused with cursor object. Also I am doubtful about what is the difference between cursor.close() and connection.close() function in terms of resource release.
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In computer science, a database cursor is a mechanism that enables traversal over the records in a database. Cursors facilitate subsequent processing in conjunction with the traversal, such as retrieval, addition and removal of database records.
It is an object that is used to make the connection for executing SQL queries. It acts as middleware between SQLite database connection and SQL query. It is created after giving connection to SQLite database.
To create a connection between the MySQL database and Python, the connect() method of mysql. connector module is used. We pass the database details like HostName, username, and the password in the method call, and then the method returns the connection object.
A cursor is an object which helps to execute the query and fetch the records from the database. The cursor plays a very important role in executing the query.
This is the object used to interact with the database. Do not create an instance of a Cursor yourself. Call connections.Connection.cursor (). See Cursor in the specification. Execute stored procedure procname with args.
You can create Cursor object using the cursor () method of the Connection object/class. Following are the various methods provided by the Cursor class/object. This method is used to call existing procedures MySQL database. This method is used to close the current cursor object.
Depending on the underlying implementation it may be possible to generate several cursors sharing the same connection to a database.
The MySQLCursor of mysql-connector-python (and similar libraries) is used to execute statements to communicate with the MySQL database. Using the methods of it you can execute SQL statements, fetch data from the result sets, call procedures. You can create Cursor object using the cursor () method of the Connection object/class.
The cursor paradigm is not specific to Python but are a frequent data structure in databases themselves.
Depending on the underlying implementation it may be possible to generate several cursors sharing the same connection to a database. Closing the cursor should free resources associated to the query, including any results never fetched from the DB (or fetched but not used) but would not eliminate the connection to the database itself so you would be able to get a new cursor on the same database without the need to authenticate again.
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As others mention, a Connection() is the network connection to the database, and it's only real use is to return cursors. PEP-249, where DBApi 2.0 is specified, does not clearly define what exactly a connection or cursor is, nor what the close() method on each must do; only that <module>.connect() must return an instance of <module>.Connection , that <module>.Connection.cursor() must return an instance of <module>.Cursor , and <module>.Cursor.execute() should invoke the statement provided and return the resulting rows. In particular, it does not define a <module>.Connection.execute() , although specific implementations are free to implement them as extensions.
Depending on those extensions is probably unwise, though, since it means you won't have as portable code. DBApi makes this two-level requirement because having an execute on the connection without an intermediate object can be difficult on some databases.
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