Database systems handle queries represented in different character sets. A database system allows data stored in the same database column to be represented in different character sets. In response to a query, the database system returns query results in the same character set as the received query even though the data stored in the database column is in a different character set. The database system creates and maintains a metadata table that stores attributes of database columns. The attributes of database columns include, among others, a data type, and a collation attribute. By tracking the collation attributes for data stored in database columns, the database system determines whether to convert data stored in a database column when processing database queries.