I have 2 columns col1 and col2
is it possible to make a constraint to not be able to add the same email two times in this columns, only using indexes?
The Question has been edited to: "Is it possible to define a constraint so as to be unable to add the same email twice in these columns for the same record, using only indexes?"
But it is my fault, I did not give enough details. When I have a unique column. I can not repeat a entry in this column. What I need is to expand this "unique" to a second column, so that any entry made in the first column, should not be possible entered to the second column at all.
I can do it using a external program by consequently adding the entries for this two columns in a array and always checking the array before entering something to this two columns. But the solution a joke, it is sub-optimal, because by extrapolation we do not need databases any more we can use arrays.
Is this possible using just mysql, or do I need "my array" ?