列含糊不清的錯誤

Question

我有這個代碼

select people_id,first_name 
FROM people , PUBAUTHOR_PEOPLE 
WHERE people.people_id = PUBAUTHOR_PEOPLE. people_id 

它說列定義不明確，有人知道為什么以及如何解決這個問題嗎？

Answer 1

您應該在表名之前添加表名，如下所示

select people.people_id,people.first_name 
FROM people , PUBAUTHOR_PEOPLE 
WHERE people.people_id = PUBAUTHOR_PEOPLE. people_id 

我建議您使用以下別名來使代碼更具可讀性

select p.people_id,p.first_name 
FROM people p, PUBAUTHOR_PEOPLE pp
WHERE p.people_id = pp.people_id 

我還建議您使用以下聯接

select p.people_id,p.first_name 
FROM people p
join PUBAUTHOR_PEOPLE pp on p.people_id = pp.people_id

現在它更具可讀性，不是嗎？

Answer 2

之所以抱怨，是因為兩個表都有一個名為“ people_id”的列，因此您必須指定要從哪個表讀取數據（即使由於連接條件而相同），如下所示：

SELECT      people.people_id,
            first_name 

FROM        people, PUBAUTHOR_PEOPLE 

WHERE       people.people_id = PUBAUTHOR_PEOPLE.people_id