SQL語法錯誤 - 奧利凡德的庫存

Question

我工作throught挑戰這裏詳述： https://www.hackerrank.com/challenges/harry-potter-and-wands

，並想出了這個解決方案，但我得到一個語法錯誤消息，而不是或結果我期待。我的代碼：

With 
    m As (Select 
    w.power, 
    wp.age, 
    Min(w.coins_needed) As min_coins 
From 
    wands w Join 
    wands_property wp 
    On wp.code = w.code 
Where 
    wp.is_evil = 0 
Group By 
    w.power, wp.age) 
Select 
w.id, 
wp.age, 
w.coins_needed, 
w.power 
From 
wands w Join 
wands_property wp 
On wp.code = w.code 
Join m 
On m.power = w.power And m.age = wp.age And m.min_coins = 
w.coins_needed 
Where 
wp.is_evil = 0 
Order By 
w.power Desc, 
wp.age Desc, 
w.coins_needed Desc 

從hackerrank錯誤消息：

ERROR 1064 (42000) at line 1: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'm As (Select 
    w.power, 
    wp.age, 
    Min(w.coins_needed) As min_coins' at line 2 

我看不出有什麼不妥。我錯過了什麼？

Answer 1

在MySQL中，則應該使用（選擇...）一個選擇，而不是與

如

select * from (Select 
    w.power, 
    wp.age, 
    Min(w.coins_needed) As min_coins 
From 
    wands w Join 
    wands_property wp 
    On wp.code = w.code 
Where 
    wp.is_evil = 0 
Group By 
    w.power, wp.age) t 
...... 

望着你的代碼

Select w.id, wp.age, w.coins_needed, w.power 
From (Select w.power, wp.age, Min(w.coins_needed) As min_coins 
    From wands w Join wands_property wp On wp.code = w.code 
    Where wp.is_evil = 0 Group By w.power, wp.age) m 
Join wands_property wp On wp.code = w.code 
Join m On m.age = wp.age 
And m.power = w.power 
And m.min_coins = w.coins_needed 
Where wp.is_evil = 0 
Order By w.power Desc, wp.age Desc, w.coins_needed Desc 

您查詢必須rethinked因爲至少你有以下問題

1. 您沒有表W¯¯，因爲你已經使用了相關的選擇命名米結果表因此可能會

2. 你指的是w.id，但在查詢中還沒有AW表

3. 你是選擇一個min_coins但你沒有這個列在主要選擇，所以不可用於where /和子句

4. w.code列不可用（w表不存在，至少exsite米表，但你無論如何都不要碼列）

所以你應該從第一部分（from（）子句中的子選擇）重建你的查詢重建你的查詢