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Description of the illustration greatest.gif


GREATEST returns the greatest of the list of one or more expressions. Oracle Database uses the first expr to determine the return type. If the first expr is numeric, then Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that datatype before the comparison, and returns that datatype. If the first expr is not numeric, then each expr after the first is implicitly converted to the datatype of the first expr before the comparison.

Oracle Database compares each expr using nonpadded comparison semantics. The comparison is binary by default and is linguistic if the NLS_COMP parameter is set to LINGUISTIC and the NLS_SORT parameter has a setting other than BINARY. Character comparison is based on the numerical codes of the characters in the database character set and is performed on whole strings treated as one sequence of bytes, rather than character by character. If the value returned by this function is character data, then its datatype is VARCHAR2 if the first expr is a character datatype and NVARCHAR2 if the first expr is a national character datatype.

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The following statement selects the string with the greatest value:

   "Greatest" FROM DUAL;