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CHAR(length): Oracle DBMS fixed-length character string. Typically used for string columns which are less than 20 characters in length. Always used for string columns that are indexed, regardless of length. length denotes the maximum number of characters the string can contain.
VARCHAR2(length): Oracle DBMS variable-length character string. Used for non-indexed strings over 19 characters in length. length denotes the maximum number of characters the string can contain.