mysql - 如何将多个详细信息行的列汇总为一列？

Question

我有两张桌子：

table_a:

ID    |    NAME    
===============
1     |    DAN
2     |    RON
3     |    JANE

table_b:

ID    |    TEXT    
===============
2     |    APPLE
2     |    BANANA
2     |    COFFEE

我需要得到 ID 2 的结果。我在想，即使我得到一个包含 ID 2 的 TEXT 值的字符串table_b也很好，例如：

ID     |    NAME    |    TEXT
=============================
2      |    RON     | APPLE,BANANA,COFFEE

这甚至可能吗？

Answer 1

SELECT
    A.*,GROUP_CONCAT(B.`TEXT`) `TEXT`
FROM
    table_a A INNER JOIN table_b B USING (ID)
WHERE A.ID=2;

这是一个示例

mysql> DROP TABLE IF EXISTS table_a;
Query OK, 0 rows affected (0.03 sec)

mysql> DROP TABLE IF EXISTS table_b;
Query OK, 0 rows affected (0.03 sec)

mysql> CREATE TABLE table_a
    -> (ID int not null auto_increment,
    -> NAME VARCHAR(20),primary key (ID));
Query OK, 0 rows affected (0.13 sec)

mysql> CREATE TABLE table_b
    -> (ID int not null,`TEXT` TEXT,key (ID));
Query OK, 0 rows affected (0.06 sec)

mysql> INSERT INTO table_a (NAME) VALUES ('DAN'),('RON'),('JANE');
Query OK, 3 rows affected (0.06 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> INSERT INTO table_b (ID,`TEXT`) VALUES
    -> (2,'APPLE'),(2,'BANANA'),(2,'COFFEE');
Query OK, 3 rows affected (0.05 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> SELECT A.*,GROUP_CONCAT(B.`TEXT`) `TEXT`
    -> FROM table_a A INNER JOIN table_b B USING (ID) WHERE A.ID=2;
+----+------+---------------------+
| ID | NAME | TEXT                |
+----+------+---------------------+
|  2 | RON  | APPLE,BANANA,COFFEE |
+----+------+---------------------+
1 row in set (0.00 sec)

试试看 ！！！

要获取 table_a 中可用的所有值以及可以从 table_b 分组的任何值：

SELECT
    A.*,IFNULL(GROUP_CONCAT(B.`TEXT`),'') `TEXT`
FROM
    table_a A LEFT JOIN table_b B USING (ID)
GROUP BY A.ID

这是该示例：

mysql> use test
Database changed
mysql> DROP TABLE IF EXISTS table_a;
Query OK, 0 rows affected (0.03 sec)

mysql> DROP TABLE IF EXISTS table_b;
Query OK, 0 rows affected (0.02 sec)

mysql> CREATE TABLE table_a (ID int not null auto_increment,NAME VARCHAR(20),primary key (ID));
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE table_b (ID int not null,`TEXT` TEXT,key (ID));
Query OK, 0 rows affected (0.03 sec)

mysql> INSERT INTO table_a (NAME) VALUES ('DAN'),('RON'),('JANE');
Query OK, 3 rows affected (0.02 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> INSERT INTO table_b (ID,`TEXT`) VALUES (2,'APPLE'),(2,'BANANA'),(2,'COFFEE');
Query OK, 3 rows affected (0.00 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> SELECT A.*,IFNULL(GROUP_CONCAT(B.`TEXT`),'') `TEXT`
    -> FROM table_a A LEFT JOIN table_b B USING (ID) GROUP BY A.ID;
+----+------+---------------------+
| ID | NAME | TEXT                |
+----+------+---------------------+
|  1 | DAN  |                     |
|  2 | RON  | APPLE,BANANA,COFFEE |
|  3 | JANE |                     |
+----+------+---------------------+
3 rows in set (0.00 sec)

mysql>

Answer 2

你只需要使用GROUP_CONCAT

SELECT  a.ID, a.Name, GROUP_CONCAT(b.text) textList
FROM    table_a a
        INNER JOIN table_b b
            ON a.ID = b.ID
-- WHERE ...if you want extra condition.
GROUP BY a.ID, a.Name

• SQLFiddle 演示
• GROUP_CONCAT

Answer 3

您可以使用GROUP_CONCATMySQL 中的函数来组合相关表中的结果：

select
  a.id,
  a.name,
  group_concat(b.text) text
from
  table_a a
join
  table_b b on a.id = b.id
group by a.id

样本输出：

| ID | NAME |         TEXT         |
------------------------------------
|  2 |  RON |  APPLE,BANANA,COFFEE |

演示：http ://www.sqlfiddle.com/#!2/e3584/9