Package stmt
source code
MySQL Statement API.
The Statement API is a way to pre-parse a SQL statement on the server-side, and
then reuse that SQL statement without requiring the server to reparse it. It
also transfers the data as raw binary data, so there does not need to be an
intermediate conversion to and from a string (thus the statement API does not
use the mysql.conversion code).
A SQL statement is represented by the mysql.stmt.Statement object. Parameters
for the statement are stored in a mysql.stmt.bind_in.Input_Bind object. You
can simply update the value inside the Input_Bind object and re-execute the
query. The position in the SQL statement where you want your bound input value
to exist is denoted by a question mark. The question marks are processed in
left-to-right order.
The results are placed into mysql.stmt.bind_out.Output_Bind objects. You
must prepare these objects before you execute the statement.
An example of selecting data would be:
class bar:
def __init__(self, connection):
self.thing = None
self.foo = None
self.s = connection.new_statement('SELECT foo FROM bar WHERE thing=?')
self.s.bind_input(mysql.stmt.bind_in.In_Int(self, 'thing'))
self.s.bind_output(mysql.stmt.bind_out.Out_Varchar(self, 'foo'))
b = bar()
b.thing = 7
b.s.execute()
b.s.fetch()
print b.foo
b.thing = 8
b.s.execute()
b.s.fetch()
print b.foo
BLOB and TEXT columns can optionally use a streaming API for setting and
retrieving information. For input parameters, it automatically sets the bound
input value to an object which has a write method. For output parameters,
it similarly sets the output value to an object with a read method.
If you specified store_result as False (the default) to the execute
method, then the results are buffered on the server side. You can have only 1
live unbuffered statement object per connection in this case. If you attempt
to execute another statement, then the original statment object will be
forcefully closed. This goes for mysql.result.Result objects as well, only
one live unbuffered Result or Statement object may exist at one time. Result
objects are capable of automatically, forcefully closing Statement objects and
vice-versa.
See mysql.stmt.stmt for more detail on the Statement object itself.
See mysql.stmt.bind_in for more detail on binding input values.
See mysql.stmt.bind_out for more detail on binding output values.