Hi!

I'm not sure if i understand it right, but you have indexed the columns you used to join the two tables to find the intersection.

You can use this join also...

For your problem it would be better to add a column for each color. That way you can mark for each project what color it uses.

ID | Proj...

You can also use the FROM in SELECT, INSERTS, DELETE statements, because it is just another way to join tables.

So the (corrected) example code

update

a1

set

col =...