Oracle SQL错误ORA-00933:SQL命令未正确结束

这个查询有什么问题

SELECT F.PART_NUM, F.DESCRIPTION, S.PART_NUM, S.DESCRIPTION, F.CLASS 
FROM PART F, PART S 
WHERE F.CLASS = S.CLASS AND F.PART_NUM < customer_num =" ORDERS.CUSTOMER_NUM" 
customer_name =" 'Johnson''s"> SELECT ORDERS.ORDER_NUM, ORDER_DATE
FROM ORDERS, ORDER_LINE, PART
WHERE ORDERS.ORDER_NUM = ORDER_LINE.ORDER_NUM
AND ORDER_LINE.PART_NUM = PART.PART_NUM
AND DESCRIPTION = 'Iron';

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很难用表结构提供正确答案，也很难解释您试图实现的业务逻辑，但我认为您希望这样：

SELECT F.PART_NUM, F.DESCRIPTION, S.PART_NUM, S.DESCRIPTION, F.CLASS 
FROM PART F, PART S 
     , ( SELECT customer_num
               , customer_name
               , order_line.part_num
        FROM ORDERS, ORDER_LINE 
        WHERE ORDERS.ORDER_NUM = ORDER_LINE.ORDER_NUM ) o
WHERE F.CLASS = S.CLASS 
AND F.PART_NUM < o.customer_num 
and o.customer_name ='Johnson''s'
AND o.PART_NUM = PART.PART_NUM
AND DESCRIPTION = 'Iron';

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分号；在约翰逊之后，它有太多的问题，那就是很难开始。这里有一些明显的问题：没有使用正确的连接语法；子查询周围没有括号；>这似乎是指两列；ORDERS.CUSTOMER_NUM周围的双引号。双引号用于标识符，例如列名。对字符串文字使用单引号，例如“johnson”。什么是customer\u num=ORDERS.customer\u num customer\u name='johnson>SELECT ORDERS.ORDER\u num，ORDER\u DATE应该做什么？