SUM(expr) — identical everywhere. Note: SUM of an all-NULL group (or zero input rows) returns SQL NULL (not 0) in every one of these dialects, so callers should COALESCE(...) explicitly if a numeric default is required.
SUM(expr)
SUM(expr)— identical everywhere. Note: SUM of an all-NULL group (or zero input rows) returns SQL NULL (not 0) in every one of these dialects, so callers should COALESCE(...) explicitly if a numeric default is required.