COALESCE
COALESCE returns the first non-null expression in a list of expressions, or NULL when all of the expressions evaluate to null.
Return Value
Data type of the first argument
Syntax
COALESCE(expr [, expr ]...)
Arguments
expr can be any expression.
Examples
COALESCE(5, 8, 3) returns the value 5.
COALESCE(NULL, 8, 3) returns the value 8.
