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I’m trying to understand what this SQL (from a MySQL installation) actually does:
IF(coalesce(a.entity_id, 0) != 0, 0, 1)
While I understand what the coalesce does I don’t understand how the IF statement is modifying it.
I think:
coalesce(a.entity_id, 0) – return the first not null value,
if a.entity_id is not null you get 0 as a result of if, else 1.
a.entity_id = null => coalesce = 0 => if = 1
a.entity_id is not null => coalesce = a.entity_id => if = 0