Thanks for sharing your thought on this. This is an important issue. I will try address it in the book. Do you use web2py for teaching or development? Which one if your school if you do not mind sharing the infomation?
Massimo On Aug 14, 2:20 pm, Michael <[email protected]> wrote: > Thanks Massimo, that's a great help. I'm starting to get the hang of > it. > > I had trouble with the following: > > >>> r9=db(q2)(db.Section.id==7767|db.Section.id==7540).select() > > but realized that I needed to enclose the filters in parentheses: > > >>> r9=db(q2)( (db.Section.id==7767) | (db.Section.id==7540) ).select() > > The web2py book certainly helped with basic concepts but now that I've > ventured into real-world coding on our classroom management > application, I'm finding it difficult to extrapolate the basics to the > more complex tasks. Hence, I really appreciate your help. I'm hoping > the new version of the book will contain more advanced examples so I > can work through problems more independently. :) > > BTW, it was at this exact point that I gave up on django last summer. > I couldn't find a way to generate very complex joins using their DAL. > Eventually, I turned to web2py. It was the right decision for our > school.. > > -Michael > > On Aug 14, 12:46 pm, mdipierro <[email protected]> wrote: > > > if q1, q2, q3, ... are elementary queries like > > > db.table.field==value > > db.table.field<value > > db.table.field==db.table.otherfield+1 > > etc. > > > a SQLSet is > > > db(q1) > > db(q1&q2) same as db(q1)(q2) > > db(q1|q2) > > > "&" and "|" are the logical operators. You should not use "and" and > > "or". > > > On a SQLSet you can call .select(...) > > > db(q1|q2)(q3|q4).select(....) > > > On Aug 14, 10:46 am, Michael <[email protected]> wrote: > > > > In my last post I said r2=f1(db.Section.schoolYear==2009).select() - > > > works fine. > > > > But I'm still struggling with SQLSets. I've read through the web2py > > > book and looked at examples online. Unfortunately I can't find > > > examples that clarify complex SQLSet syntax. I don't know how best to > > > present all the scenarios I've tried so I'll just list a few below. > > > > Example 1: Trying to filter a SQLSet (f1) using multiple conditions: > > > > r2=f1(db.Section.schoolYear==2009 and db.Section.id==7540).select() > > > - results in: > > > > "ProgrammingError: The cursor's connection has been closed." > > > > Example 2: Tried to create a subset of the original set: > > > > >>>subset2=db(f1)(db.Section.id==7540) > > > >>> r6=subset2.select() > > > > Traceback (most recent call last): > > > File "C:\web2py\applications\ajaxShell/controllers/default.py", line > > > 88, in talk > > > exec(request.vars.s) in {},d > > > File "<string>", line 1, in <module> > > > File "C:\web2py\gluon\sql.py", line 2210, in select > > > query = self._select(*fields, **attributes) > > > File "C:\web2py\gluon\sql.py", line 2117, in _select > > > fields = [self._db[table].ALL for table in self._tables] > > > File "C:\web2py\gluon\sql.py", line 524, in __getitem__ > > > return dict.__getitem__(self, str(key)) > > > KeyError: 'gluon' > > > > Example 3: Tried to select specific fields from the original SQLSet: > > > > >>>r3=f1(db.Section.id==7540).select(db.Employee.name,db.Section.name,db.Cell.row,db.Cell.col,db.Cell.block,db.Period.periodStart,db.Period.periodEnd) > > > > "ProgrammingError: The cursor's connection has been closed." > > > > Example 4: Tried to create a subset from a new. more complex set: > > > > >>>set=db((db.Employee.id==db.EmployeeSection.employeeID) & \ > > > > (db.Section.id==db.EmployeeSection.sectionID) & \ > > > (db.Employee.id==9000) & \ > > > (db.Cell.id==db.SectionCell.cellID) & \ > > > (db.Section.id==db.SectionCell.sectionID) & \ > > > (db.Period.id==db.SectionCell.periodID)) > > > > >>> subset=set(db.Section.id==7540) > > > >>> subset.select() results in: > > > > "ProgrammingError: The cursor's connection has been closed." > > > > Thanks in advance for your help. > > > > -Michael --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
