錯誤1060（42S21）：重複的列名'eid'

Question

我想弄清楚爲什麼我在這個查詢中得到重複的列名。我覺得我正確地爲搜索條件添加前綴，不應該得到這個錯誤。請指教。

型號

Emp(eid:integer, ename:varchar, age:integer, salary:integer) 
Works(did:integer, eid:integer) 
Dept(did:integer, managerid:integer) //managerid is foreign key to eid 

查詢

CREATE VIEW Manager AS 
SELECT e.eid, e.ename, e2.eid, e2.ename 
FROM Emp AS e, 
    Dept AS d 
     LEFT JOIN Emp AS e2 ON d.managerid = e2.eid; 

Answer 1

嘗試在你的領域的一些別名。見下圖：

CREATE VIEW Manager AS 
SELECT 
     e.eid AS eid1, 
     e.ename AS ename1, 
     e2.eid AS eid2, 
     e2.ename AS ename2 
FROM Emp AS e, 
    Dept AS d 
LEFT JOIN Emp AS e2 ON d.managerid = e2.eid2;