On Apr 20, 2011, at 1:09 AM, bukzor wrote: > Thanks Michael. I won't be using or supporting SQL Server, so I'm > quite fine with that. > > I guess the way forward would be to install SA in develop mode and > make the changes directly?
no, to create your own SQL constructs use the compiler extension: http://www.sqlalchemy.org/docs/core/compiler.html > > Excuse my ignorance, but why would you do it that way? > Since I don't want to change any of the functionality of _Tuple I > wouldn't think a subclass would be necessary. > Also, since comparison are already captured by _CompareMixin and > represented as _BinaryExpression, I would have thought that > intercepting the compilation of _BinaryExpression in the sqlite > dialect would be the way to go. > > --Buck > > On Apr 19, 6:51 am, Michael Bayer <mike...@zzzcomputing.com> wrote: >> there's a tuple_() operator: >> >> http://www.sqlalchemy.org/docs/core/expression_api.html?highlight=tup... >> >> the object returns is _Tuple. if you wanted fancy per-dialect expression >> behavior, mmm tricky, you'd need to subclass _Tuple (or write a new object), >> intercept comparisons like __eq__(), then return *another* construct that >> represents a "Tuple Comparison", and that object would need per-dialect >> compilation rules. >> >> or you could lobby the sqlite folks to add support for the construct in the >> first place. though i doubt SQL Server has it either. >> >> On Apr 18, 2011, at 4:57 PM, bukzor wrote: >> >> >> >> >> >> >> >>> SQL-92 defines a "row value constructor" expression like "(1,2,3)" >>> which looks and behaves exactly like a Python tuple, as far as I can >>> tell. These are implemented correctly in mysql at least, and I believe >>> PostgreSQL and Oracle as well, although I don't have access to those >>> systems. >> >>> What would be the best way to deal with this type of value in >>> SQLAlchemy? >>> Should I create a RowValue class which can be visited by the various >>> dialects? >> >>> If I wanted to provide emulation for dialects which don't directly >>> support this standard, what would be the way to go? >>> For example, I'd like to be able to expand "RowValue((1,2)) >= >>> RowValue(colA, colB)" to "1 > colA or (1=colA and 2 >= ColB)" under >>> sqlite. >> >>> --Buck >> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "sqlalchemy" group. >>> To post to this group, send email to sqlalchemy@googlegroups.com. >>> To unsubscribe from this group, send email to >>> sqlalchemy+unsubscr...@googlegroups.com. >>> For more options, visit this group >>> athttp://groups.google.com/group/sqlalchemy?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
