用于将列复制到不同表的另一列的脚本

这不是正确的Oracle语法。这里有一种方法:

UPDATE T_CHARACTERISTICS c
    SET PROCESS = (SELECT d.PROCESS
                   FROM T_DOC d
                   WHERE c.ID = d.ID
                  )
    WHERE EXISTS (SELECT 1
                  FROM T_DOC d
                  WHERE c.ID = d.ID
                 );

Oracle不支持更新联接,但我们可以使用相关子查询:

UPDATE T_CHARACTERISTICS t1
SET PROCESS = (SELECT t2.PROCESS FROM T_DOC t2 WHERE t2.ID = t1.ID);