As SQL Developer said, you need to have 3 values returned by your query. If there's none, make it! For example:
select
'My graph' as series, --> this
customer_x_coord as group,
customer_y_coord as value
from customers
group by customer_x_coord,
customer_y_coord
series
value won't change (its is a constant) but it doesn't matter; now you have 3 columns, so use them to plot the graph.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…