I think you are suggesting a new Python DB-API module for accessing and querying Python namespaces.
This could probably be done by leveraging techniques from Gadfly: http://gadfly.sourceforge.net/ Alternatively, you could mirror the namespaces into sqlite and then use SQLite's SQL engine for the queries. On 03.06.2013 20:05, big stone wrote: > Hello, > > I discovered recently the power of simplifying the integration between > python and its provided database sqlite3. > > In my dream, I would like to be able to querry in "sql syntax" all objects > of python environnement. > > So, I would suggest the next evolution of the Database API to > encourage/normalize the following evolution : > - authorize also the use of parameters in place of table names, > - the provided 'parameter for a table' should be : > . a python list, > . or a dictionary, > . or query result, > . or something similar like a pandas object. > - this parameter could be used anywhere in sql, but not authorised as an > "update". > > Any "table like" object passed as a parameter will have : > - by default column names "c0", "c1", ... "cN" for each of it's N columns, > - unless it has an attribute ".description" which contains a list of string > names to be used as column title, it will be used instead of the default > values > > > Example : > ************ > #my_list is a python table > my_list=[('a', 1), ('b',2)] > > # note the usage of ':mylist' > cur=con.execute("select :mylist.* from :my_list",{'my_list':my_list}) > > rows = cur.fetchall() > columns = [col_desc[0] for col_desc in cur.description] > > print(columns) > print(rows) > > (gives:) > c0 c1 > a 1 > b 2 > > # usage for a more complex work > # copy that table in a real sql table > cur=con.execute("create table keep_me as select :mylist.* from > :my_list",{'my_list':my_list}) > > > Example of forbidden usage : > ******************************* > # this is forbidden, fails : > cur=con.execute("update :mylist.c0 set c1=c1+1 ",{'my_list':my_list}) > > Implementation : > ******************** > - the case where the list given contains a constant number of columns and a > constant type in each columns is the 'normal' one, > - If the number of columns varies, only the number of columns in the first > columns is considered (or an error can be raised), > - default types are unknown (as it works best with sqlite3), > - if any type is provided in the object (like it may be found in a query > result), it is taken. > - if a non-simple object is passed, it is transform by "cpickle", or as a > blob, or an exception is raised, as prefered for a simple implementation. > - typically for sqlite : > . the :my_list table is created as a 'create temporary table > _tmp_my_list(c0,c1) > . before the creation a "drop table if exists _tmp_my_list" is generated, > . this temporary table is destroyed at the end of the execute. > > > > Regards, > > > > _______________________________________________ > DB-SIG maillist - DB-SIG@python.org > http://mail.python.org/mailman/listinfo/db-sig > -- Marc-Andre Lemburg Director Python Software Foundation http://www.python.org/psf/ _______________________________________________ DB-SIG maillist - DB-SIG@python.org http://mail.python.org/mailman/listinfo/db-sig
