Mediawiki changed from varchar to varbinary in early 2011: War on varchar. Changed all occurrences of varchar(N) and varchar(N) binary to varbinary(N). varchars cause problems (“Invalid mix of collations” errors) on MySQL databases with certain configs, most notably the default MySQL config.
Hope this helps: http://msdn.microsoft.com/en-us/magazine/cc300805.aspx For those unfamiliar with TransactionScope, it is part of the System.Transactions namespace new to the Microsoft® .NET Framework 2.0. System.Transactions provides a transactions framework fully integrated into the .NET Framework, including but not limited to ADO.NET. The Transaction and TransactionScope classes are two of the most important classes in this namespace. … Read more
How much writing vs. reading of this table(s) do you expect? I’ve used a single audit table, with columns for Table, Column, OldValue, NewValue, User, and ChangeDateTime – generic enough to work with any other changes in the DB, and while a LOT of data got written to that table, reports on that data were … Read more
I was reading up on my django extensions, and found the django-modeltranslation plugin. It seems to do exactly what you want it to do.
Your first schema will work just fine. When you put an index on the FullPath column, use either the case-sensitive BETWEEN operator for queries, or use LIKE with either COLLATE NOCASE on the index or with PRAGMA case_sensitive_like. Please note that this schema also stores all parents, but the IDs (the names) are all concatenated … Read more
So assuming we can exclude the user table, it could be rewritten as: select * from expense, transaction where expense_id = transaction_expense_id Now if you want to apply a limit, you could do it like this: select * from expense, transaction where expense_id = transaction_expense_id and expense_id in (select expense_id from expense limit 1) Would … Read more
I’d like to write a method like <T> T getOrCreate(Class<T> klass, Object primaryKey) This won’t be easy. A naive approach would be to do something like this (assuming the method is running inside a transaction): public <T> T findOrCreate(Class<T> entityClass, Object primaryKey) { T entity = em.find(entityClass, primaryKey); if ( entity != null ) { … Read more
Suppose that some relation satisifies a non-trivial functional dependency of the form A->B, where B is a nonprime attribute. 2NF is violated if A is not a superkey but is a proper subset of a candidate key 3NF is violated if A is not a superkey You have spotted that the 3NF requirement is just … Read more
To add the column with a default and then delete the default, you can name the default: ALTER TABLE tbl ADD col INTEGER NOT NULL CONSTRAINT tbl_temp_default DEFAULT 1 ALTER TABLE tbl drop constraint tbl_temp_default This filled in the value 1, but leaves the table without a default. Using SQL Server 2008, I ran this … Read more
August 2022: Note that the below is flawed and doesn’t work when moving a movie down the list. I’ve posted a new answer here which fixes this issue. If you use a combination of the position and a timestamp that the user put a movie in a given position rather than trying to maintain the … Read more