SQL INSERT WITH JOIN

Question

我有一個mysql查詢的問題。

這是我的2個表：

player_locations:

ID | playerid | type | location 
---|----------------------- 

和users:

ID | playername | [..] 
----|-------------------- 
1 | example1 | ... 

我要插入player_locations如下：

ID | playerid | type | location 
---|----------------------- 
1 |  1  | 5 | DOWNTOWN 

而這就是我的查詢：

INSERT INTO player_locations (id, type, location) 
    SELECT u1.ID as playerid, 
     d.type, 
     d2.location 
    FROM users u1 
    INNER JOIN users u2 
    ON 1 = 1 
    INNER JOIN (SELECT 5 as type 
     FROM DUAL) d 
    INNER JOIN (SELECT "DOWNTOWN" as location 
     FROM DUAL) d2 
    ON 1 = 1 
    WHERE u1.playername = "example1"; 

但是，當我在users有6排它player_locations

Answer 1

爲什麼不直接寫這個？

INSERT INTO player_locations(id, type, location) 
    SELECT u.ID as playerid, 5 as type, 'DOWNTOWN' as location 
    FROM users u 
    WHERE u.playername = 'example1'; 

自連接沒有任何意義。您在查詢中沒有使用來自u2的任何信息，因此它只是乘以行數。額外的常量連接是不必要的。

Answer 2

插件6個相同的行以WHERE子句出來，把你的選擇中在插入的（）和那應該爲你做。