SQL INSERT WITH JOIN

Question

我有一个mysql查询的问题。

这是我的2个表：

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 

而这就是我的查询：

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，当我在users有6排它player_locations

Answer 1

为什么不直接写这个？

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'; 

自连接没有任何意义。您在查询中没有使用来自u2的任何信息，因此它只是乘以行数。额外的常量连接是不必要的。

Answer 2

插件6个相同的行以WHERE子句出来，把你的选择中在插入的（）和那应该为你做。