Database Level Collation Issues

Changing an existing database to a new collation isn’t reliably achievable using the sqlservr -q startup method, which only changes the server default collation and often fails because single-user mode is easily taken by other services (SQL Agent, monitoring tools, etc.) before your session connects. More importantly, this method does not update existing database objects, so dependencies, indexed views, computed columns, and column-level collations can cause inconsistent results. The only fully reliable approach is either to rebuild the system databases using SQL Server Setup with the desired collation (which also ensures tempdb matches), or to change the database collation and then explicitly alter every affected column, index, and constraint since SQL Server cannot automatically propagate collation through all objects in complex databases. This is why your command works only part of the time: it isn’t a supported or deterministic way to rewrite database-level or object-level collations.