all we (when I say we, I mean *I*) do is dump the schema to a text file and make sure that it's up to date in cvs.
not rocket science, but it means that all the developers are up to speed.... yeah like all two of us :) jaseb -----Original Message----- From: Tomm Carr [mailto:[EMAIL PROTECTED]] Sent: 11 December 2002 07:20 To: JDJList Subject: [jdjlist] Re: SQL Schema version/maintenance ----- Original Message ----- From: "M.Francis" <[EMAIL PROTECTED]> > Tomm Carr wrote: > > If the erd in ERwin contains triggers and stored procedures, then it can be > > automated to a large extent. > > The erd does not need to contain the triggers in order for Erwin to > assist with the dependencies. The metadata in the schema is > used to determine the current db objects' dependencies. Right, but it was not the dependencies I was thinking about. Remember the original question -- is there a tool to automatically generate the necessary steps to incorporate modifications to the schema design. If part of that modification is the addition of a column to a table (or the removal of a column, the renaming of a column, ...) then chances are good that one or more triggers will have to be changed modified to reflect that change. If the trigger is part of the erd, the tool will know the trigger has been modified and generate the proper DROP TRIGGER/CREATE TRIGGER code. If the trigger is not part of the erd, this step must be inserted manually. Even if the trigger does not change, any alteration of the table would require the existing triggers be recompiled. > > > But ERwin can only generate a script of the > > necessary ddl. A modification could very well need some dml. > > Agreed. > > But, one is allowed to set a default value for the column definition, > or where one is not appropriate, modify the generated dml script with a > work around of inserting an appropriate value to address > the issue you've raised about the non-nullable column. Which is exactly what I said in the next paragraph. > This manual step is necessary thing because it is a judgement call made > by the user as to what value is appropriate in those cases when a column > does not have a default value setting. Which brings you into complete agreement with what I said in my first response. > It would be odd to have a a modelling tool begin to perform data manipulation > that are not part of the ddl construct. > > > > Consider the case of adding a column and the column is set to NOT NULL. > > Before the contraints for the table are re-enabled, the column must be > > populated with data. It may be a simple matter to manually insert the > > necessary code into the generated script, but this just shows the > > impossibility of ever *fully* automating the creation of the complete > > script. > > I agree with the premise you had initially noted. It is difficult yes, > impossible no. (It is resource/time intensive to come up with a matrix and > a viable solution as well as maintain the same for future with unforeseeable changes > ahead...) There is not much that is technically impossible, but there are other barriers that prevent a project from seeing the light of day. Perhaps "infeasabiltiy" would have been a better word to use. > Still, wanting automation of data manipulation affected by ddl changes, > is akin to expecting a data scrubber with a modelling tool. I'm not sure > that's what the two functionally distinct aspects to be handled by the same tool. Exactly. Any data modeling tool manipulates only the metadata, not the data. Some modifications to a schema may require manipulation of the data. Ergo, modifications to a schema cannot always be fully handled by a data modeling tool -- or any existing tool that I know of. Tomm -- Wit is cultured insolence. - Aristotle ____________________________________________________ To change your JDJList options, please visit: http://www.sys-con.com/java/list.cfm Be respectful! Clean up your posts before replying ____________________________________________________ ____________________________________________________ To change your JDJList options, please visit: http://www.sys-con.com/java/list.cfm Be respectful! Clean up your posts before replying ____________________________________________________
