I've been given a Sybase
.db file by a client and I need to import that into a new SQL Server database so that I may see the data as well as the tables and their relationships, any ideas on how that might be done shall be really appreciated :)
Since both Sybase and SQLServer share the same SQL dialect (T-SQL), I'd generate the DDL statements from the existing database (it will require a Sybase server) to build the SQL Server database and the an SSIS task to copy data between databases.
I don't know if it is possible to SQLServer to just open a Sybase file, but, albeit the same origins, I don't believe there's any kind of binary compatibility between inner formats of this two DBMS.
If it's a dump file, load it into a development database using the load command. Alternatively you can use a working production system to obtain a new dump. You can the transfer it from the sybase db to the ms sql server db using Microsoft's SSMA tool.
The download link for SSMA is below. Microsoft SQL Server Migration Assistant v5.3 for MySQL