What is one limitation of AMC SQL?

The correct answer is Some common SQL functions are not currently supported because Amazon Marketing Cloud (AMC) SQL has certain limitations in terms of the functions it supports. While AMC SQL is based on standard SQL syntax, not all commonly used SQL functions are available within the platform. For instance, functions such as certain window functions or more complex analytic operations may not be supported, requiring users to adapt their queries to work within the constraints of the available functions. The other options are incorrect: AMC SQL does support filtering query results based on date range, and it allows joining tables from different databases, as long as the necessary data is available within the same instance or schema. Therefore, the main limitation is the absence of support for some SQL functions.