On Sep 10, 2010, at 11:47 AM, Jon Nelson wrote: > I found something interesting recently: I have a table with a boolean column. > When I wrote (low-level) sqlalchemy code, I used constructs like this: > > query = query.where(table.c.boolean_column==True) > > and when executed the query uses '='. > > In the psql console, however, I had been using 'boolean_column IS > true', and my indexes are partial indexes which specify the same > (using IS not equals). > > When I use ==None then I get 'IS NULL'. > > I'm not sure which is the totally *right* way to do this, but there is > a difference. If I wanted to get IS true (or IS false) out of > sqlalchemy, how would I do it?
IS is important for NULL, since nothing can be "equals" to NULL in relational DBs. NULL = NULL returns false. "IS true" and "IS false" is not so critical, however, unless you need to compare NULL columns to "false" and expect to get a "true" value for that (which I would not recommend; I'd test for IS NULL before comparing to anything else). It could be changed by overriding the compilation for _BinaryExpression but I don't think its necessary. > > > -- > Jon > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@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 sqlalch...@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.
