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title: "Beam ZetaSQL function call rules"
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# Beam ZetaSQL function call rules

The following rules apply to all functions unless explicitly indicated otherwise in the function description:

+ For functions that accept numeric types, if one operand is a floating point
  operand and the other operand is another numeric type, both operands are
  converted to FLOAT64 before the function is
  evaluated.
+ If an operand is `NULL`, the result is `NULL`, with the exception of the
  IS operator.

+ For functions that are time zone sensitive (as indicated in the function
  description), the default time zone, UTC, is used if a time
  zone is not specified.