You didn't mistunderstand the purpose (However it's not an explicit goal of FnordMetric to substitute chart.io)

Here is an example that connects to a MySQL database on localhost: https://github.com/paulasmuth/fnordmetric/blob/master/fnordm...

Note that the IMPORT statement might be a bit misleading. The IMPORT statement only creates a "virtual table", it doesn't actually copy any data. As much of the query as possible is pushed down into MySQL/the external data source and the charts will be generated from the query result that is returned by the external data source.