Question

我尝试使用＆＃34; JOIN ＆＃34;添加一个列到表中命令。但我一直有一个含糊不清的错误：

ORA-00918：列模糊定义

SELECT ORDER_NUM, CUSTOMER_NUM, ORDER_DATE+20 AS PROMOTION_DATE, CUSTOMER.CUSTOMER_NAME
FROM ORDERS, CUSTOMER
WHERE ORDERS.CUSTOMER_NUM = CUSTOMER.CUSTOMER_NAME;

Answer 1

如果2个表具有相同名称的列，则需要告诉DB要采用哪个列。您可以通过在列名称前添加表名来完成此操作。

SELECT ORDERS.ORDER_NUM,  
       CUSTOMER.CUSTOMER_NUM,
       ORDERS.ORDER_DATE+20 AS PROMOTION_DATE, 
       CUSTOMER.CUSTOMER_NAME
FROM ORDERS
JOIN CUSTOMER ON ORDERS.CUSTOMER_NUM = CUSTOMER.CUSTOMER_NAME;

Answer 2

在select子句中，您将错过列CUSTOMER_NUM的表别名。

SELECT ORDER_NUM, ORDERS.CUSTOMER_NUM, ORDER_DATE+20 AS PROMOTION_DATE, CUSTOMER.CUSTOMER_NAME
FROM ORDERS, CUSTOMER
WHERE ORDERS.CUSTOMER_NUM = CUSTOMER.CUSTOMER_NAME;

Answer 3

似乎列名模糊的问题。如果两个表具有相同的列名，则只需将列写为[tablename].[columnname]。如果ORDERS.CUSTOMER_NUM是Customer_NUM表的列。

，则为Orders

所以它应该是这样的：

SELECT ORDERS.ORDER_NUM, ORDERS.CUSTOMER_NUM,ORDERS.ORDER_DATE+20 AS PROMOTION_DATE,CUSTOMER.CUSTOMER_NAME
FROM ORDERS
Inner JOIN CUSTOMER
ON ORDERS.CUSTOMER_NUM = CUSTOMER.CUSTOMER_NAME

SQL加入错误＆＃34;歧义＆＃34;

3 个答案: