Why does alias not always work as expected?

[marcus_doron]

In my Results, for each event, I can only get field A OR field B.
I created two aliases: A=C, B=C
So each event should have C with a value.

But in the result, I can see that sometimes C gets value A, sometimes value B, and sometimes Blank.

[gcusello]

Hi marcus_doron,
If you have only one of the three field with value or if you have an order of importance in your fields, you could use the coalesce function:

| eval C=coalesce(C,A,B)

in this way your C field take value, in order, from C, A, B.

Bye.
Giuseppe