How to make grouped column visualization out of simple select?

[eugene_s1]

I want to do a column chart with multiple groups (just like the first one described on https://cloud.google.com/looker/docs/column-options). For that I have a very simple select statement: `SELECT x, y1, y2, y3 FROM atable` where I want to have groups of y1, y2, y3 for every x point. How should I transform this select statement so column visualization will recognize it as applicable for grouped display?