A variety of upgrading options are available. After migrating the data and queries to SQL Server, the Access database can be linked to the SQL database. However, certain data types are problematic, most notably "Yes/No". In Microsoft Access there are three states for the Yes/No (True/False) data type: empty, no/false (zero) and yes/true (-1). The corresponding SQL Server data type is binary, with only two states, permissible values, zero and 1. Regardless, SQL Server is still the easiest migration. Retrieving data from linked tables is optimized to just the records needed, but this scenario may operate less efficiently than what would otherwise be optimal for SQL Server. For example, in instances where multi-table joins still require copying the whole table across the network.