[英]How to do a mysql select query on a table with two columns of foreign keys that relate to another table of names
我有两个表,表A具有两个外键列( div_player1_id
, div_player2_id
)和Table B
具有涉及在所述外键的主键Table A
。 我试图写一个选择查询,将输出的名字player1
和player 2
一行。
wp_divisions - Div_id, div_player1_id, div_player2_id
wp_players - ID, display_name
Output = Div_Id, display_name of Player1, display_name of Player2
Select display_name FROM wp_players INNER Join wp_divisions where wp_players.ID = wp_divisions.div_player1_id;
这显示了Player1名称。
Select display_name FROM wp_players INNER Join wp_divisions where wp_players.ID = wp_divisions.div_player2_id;
这显示了Player2名称。
我想在一个表中输出:
Division Player 1 Player 2
1001 Joe Smith Tom Jones
但是无法适应我的需求
不确定如何编写代码。
您必须两次将wp_divisions
与wp_players
一起加入:
select
d.Div_id,
p1.display_name player1,
p2.display_name player2
from wp_divisions d
inner join wp_players p1 on p1.ID = d.div_player1_id
inner join wp_players p2 on p2.ID = d.div_player2_id
如果存在div_player1_id
或div_player2_id
为null
的情况,则使用left
联接而不是inner
联接。
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