I inherited a mixed collation environment with more collations than I can count on one hand.  The different collations require workarounds to avoid "cannot resolve collation conflict" errors and those workarounds kill performance due to non-sargable expressions.  Dealing with mixed collations is a real pain so I strongly recommend you standardize on a single collation and deviate only after careful forethought.  Here's a brief overview of collations and some guidance to help you choose the right collation for your organization and new SQL installations. Collation Overview A collation determines the rules SQL Server uses to compare and sort character data.  These rules...