Comments on: Schema Evolution Confusion / Example Case

By: SQL Tutorials

SQL Tutorials — Fri, 01 May 2009 02:44:44 +0000

You know, the thing about SQL is, that there is virtually nothing that can replace it.

Does anyone know if a substitute exists for sql? I mean besides MS SQL and Oracle and all that jazz. Thanks.

By: SQL Tutorials

SQL Tutorials — Fri, 01 May 2009 02:44:14 +0000

Does anyone know if there is another language or set of commands beside SQL for talking with databases?

I’m working on a project and am doing some research thanks

By: buriy

buriy — Mon, 06 Aug 2007 03:14:08 +0000

IMO the right behavior is to ask user to confirm data loss when changing v1 => v2.

By: SmileyChris

SmileyChris — Fri, 03 Aug 2007 21:48:35 +0000

I would argue that the exact path from v1 => v3 can definitely be important!

class Russ(models.Model):
____”this model is going to have a bit of a day (v1)”
____a = models.CharField(maxlength=200)

class Russ(models.Model):
____”this model is going to have a bit of a day (v2)”
____b = models.CharField(maxlength=200, null=True)
____c = models.CharField(maxlength=200, aka=’a')

class Russ(models.Model):
____”this model is going to have a bit of a day (v3)”
____a = models.CharField(maxlength=200, aka=’b', null=True)
____b = models.CharField(maxlength=200, aka=’c')

Tester 1 & 2 have the same database contents at v1: [Russ(a='first')]

Tester 1 goes from v1 => v2 => v3. Now he has [Russ(a=None, b='first')]
Tester 2 merges from 1’s work and evolves from v1 => v3. Now he has [Russ(a='first', b=None)] (or error since b shouldn’t be able to be NULL).

Since you have “lost” what happened in v2, it’s not possible for Tester 2 to guess what should have happened.