Say I’ve got a SQL sales database where each record (row) has a category field assigning the record into one of several groups (“grocery”, “pharmacy”, “automotive”, etc.), along with sales amount, and date/time of sale. Is it possible to construct a line-chart visualization in Redash which plots the sales of each category as its own line? (IOW, each category is its own data series.) For example, if there were 100 records in the database, with 90 records in one category, and 10 in another, the result would be a line chart with two connected lines - one with 90 points, and the other with 10.

Yes, you can do this using the Group field on the chart editor.