An expression of the exact numeric or approximate numeric data type categories, or types that are implicitly convertible to float.
The precision to which numeric_expression is to be rounded. When length is a positive number, numeric_expression is rounded to the number of decimal places specified by length. When length is a negative number, numeric_expression is rounded on the left side of the decimal point, as specified by length.
The type of operation to perform. When function is omitted or has a value of 0 (default), numeric_expression is rounded. When a value other than 0 is specified, numeric_expression is truncated.