Hi list!
I have tried to create a function to return a statement that copies
data between tables. I have come up with this:
def copy_table(from_table, to_table, whereclause = None):
columns_str = ", ".join(from_table.columns.keys())
from_select = select([columns_str]).where(whereclause)
from_select_str = str(from_select)
return text("""INSERT INTO %(to_table)s (%(columns_str)s)
\n%(from_select_str)s""" % params )
(Don't know if this is mysql-only syntax, but it works for me at
least) If there is a better way of doing this, please enlighten me.
Now I'd like to add support for where-clauses, and I'm a bit stuck. I
tried something like this:
def copy_table(from_table, to_table, whereclause = None):
columns_str = ", ".join(from_table.columns.keys())
from_select = select([columns_str]).where(whereclause)
from_select_str = str(from_select)
where_str = whereclause.compile()
params = locals()
params.update(whereclause.compile().params)
return text("""INSERT INTO %(to_table)s (%(columns_str)s) \nWHERE
%(where_str)s""" % params )
...which didn't quite work, I end up with %s in my query.
Nicest would be if I could somehow inherit from Insert or
ClauseElement, so generative where-clauses work, but I can't quite
figure out how to combine that with the visitor pattern used for the
different backends. Any hints on how I would accomplish this?
-- Joakim
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