MySQL删除左连接上的重复列，3个表
我有三个表，每个表都有一个外键.当我执行连接时，我得到重复的列.
I have three tables, each have a foreign key. When I perform a join, I get duplicate columns.
给定
mysql> describe Family;
+---------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+-------------+------+-----+---------+-------+
| HEAD_name | varchar(45) | NO | PRI | | |
| Family_Size | int(11) | NO | | | |
| Gender | char(1) | NO | | | |
| ID_Number | int(11) | NO | | | |
| DOB | date | NO | | | |
| Supervisor_ID | int(11) | NO | MUL | | |
+---------------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)
mysql> describe SUPERVISOR;
+-------------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+---------------+------+-----+---------+-------+
| Supervisor_ID | int(11) | NO | PRI | | |
| Supervisor_Name | varchar(45) | NO | | | |
| Supervisor_Number | decimal(10,0) | NO | | | |
| Center_ID | int(11) | NO | MUL | | |
+-------------------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
mysql> describe CENTER;
+-----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| Center_ID | int(11) | NO | PRI | | |
| Location | varchar(45) | NO | | | |
+-----------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
我的查询语句:
SELECT * from Family
JOIN SUPERVISOR on ( Family.Supervisor_ID = SUPERVISOR.Supervisor_ID)
JOIN CENTER on (SUPERVISOR.Center_ID = CENTER.Center_ID);
我的目标是从连接中获取所有列中的一行，而没有重复的列.那么我应该使用的 SQL 语句语法是什么?
My objective is to get one row of all the columns from the join without duplicate columns. So what is the SQL statement syntax that I should use?
推荐答案
默认情况下，如果您使用 *，MySQL 将返回所有表的所有列.您需要在查询中明确输入列名，以按照您想要的方式检索它们.使用查询如下:
By default MySQL will return all columns for all tables if you use *. You will need to explicitly enter column names in your query to retrieve them the way you want. Use the query as follows:
SELECT A.HEAD_name, A.Family_Size, A.Gender, A.ID_Number, A.DOB,
B.Supervisor_ID, B.Supervisor_Name, B.Supervisor_Number,
C.Center_ID, C.Location
FROM Family A
JOIN SUPERVISOR B on ( A.Supervisor_ID = B.Supervisor_ID)
JOIN CENTER C on (B.Center_ID = C.Center_ID);
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