如何在不重复 mysql 中的列的情况下连接表

Question

我有两个表：

table1 (限制 5):

+--------------+
| TF_ID        |
+--------------+
| T139297_1.02 | 
| T025433_1.02 | 
| T025429_1.02 | 
| T045327_1.02 | 
| T088966_1.02 | 
+--------------+

table2（限制 5）：

+--------------+-----------+------------+-------------+
| TF_ID        | Family_ID | TSource_ID | DBID        |
| T000001_1.02 | F001_1.02 | TS19_1.02  | FBgn0085089 |
| T000002_1.02 | F002_1.02 | TS07_1.02  | AMAG_03406  | 
| T000003_1.02 | F002_1.02 | TS07_1.02  | AMAG_05299  | 
| T000004_1.02 | F002_1.02 | TS07_1.02  | AMAG_10904  |
| T000005_1.02 | F002_1.02 | TS07_1.02  | AMAG_15258  | 
+--------------+-----------+------------+-------------+

我想通过 TF_ID 列连接两个表，我试过这个：

select a.TF_ID, b.TF_ID, b.Family_ID from table1 a, table2 b where a.TF_ID=b.TF_ID;

输出如下：

+--------------+--------------+-----------+
| TF_ID        | TF_ID        | Family_ID |
+--------------+--------------+-----------+
| T014411_1.02 | T014411_1.02 | F070_1.02 | 
| T014431_1.02 | T014431_1.02 | F070_1.02 | 
| T014439_1.02 | T014439_1.02 | F070_1.02 | 
| T014447_1.02 | T014447_1.02 | F070_1.02 | 
| T014450_1.02 | T014450_1.02 | F070_1.02 |

TF_ID 列不重复怎么办？我是数据库新手，请帮忙

Answer 1

只需select一次；您不必 select 两次。示例：

SELECT a.TF_ID, b.Family_ID
FROM table1 a, table2 b
WHERE a.TF_ID=b.TF_ID;

更好的是，使用USING:

SELECT a.TF_ID, b.Family_ID
FROM table1 a
    LEFT JOIN table2 b USING (TF_ID);

Answer 2

select a.TF_ID, b.Family_ID, b.TSource_ID,b.DBID 从表 1 在 a.TF_ID=b.TF_ID;

上左连接表 2 b

如何在不重复 mysql 中的列的情况下连接表

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