MySQL查詢：如何修復錯誤1052（模糊列）

Question

當我同時運行以下兩個查詢時，我總是收到錯誤消息：CUST_NUM不明確。 我怎樣才能解決這個問題？

SELECT  INV_NUM, CUST_NUM, CUST_LNAME, CUST_FNAME, INV_DATE, INV_AMOUNT
FROM    CH08_INVOICE i 
INNER JOIN CH08_CUSTOMER c1 ON (i.CUST_NUM = c1.CUST_NUM)
WHERE   CUST_BALANCE>=1000;


SELECT CUST_LNAME, CUST_FNAME 
FROM CH08_CUSTOMER c1 JOIN CH08_CUSTOMER_2 c2
ON (c1.CUST_LNAME = c2.CUST_LNAME AND c1.CUST_FNAME = c2.CUST_FNAME);

Answer 1

SELECT i.INV_NUM, i.CUST_NUM, i.CUST_LNAME, i.CUST_FNAME, i.INV_DATE, i.INV_AMOUNT FROM CH08_INVOICE i INNER JOIN CH08_CUSTOMER c1 ON (i.CUST_NUM = c1.CUST_NUM) WHERE i.CUST_BALANCE>=1000;

SELECT c1.CUST_LNAME, c1CUST_FNAME FROM CH08_CUSTOMER c1 JOIN CH08_CUSTOMER_2 c2 ON (c1.CUST_LNAME = c2.CUST_LNAME AND c1.CUST_FNAME = c2.CUST_FNAME);

請檢查此查詢

Answer 2

列不明確意味着數據庫不知道它必須使用哪個表。

嘗試使用

SELECT  INV_NUM, i.CUST_NUM ...

要么

SELECT  INV_NUM, c1.CUST_NUM ...

明確定義表格。