在SQL

Question

我具有以下表格结构

表1

+-----+---------+
| id  | user_id |
+-----+---------+
| 1   | 123     |
| 2   | 456     |
+-----+---------+

表2

+-----+----------+------+------+
| id  | user_id  | data | name |
+-----+----------+------+------+
| 1   | 123      | abc  | Tom  |
| 2   | 123      | xyz  | Jon  |
| 3   | 456      | pqr  | Johny|
+-----+----------+------+------+

我想在每个用户的 Table2 中列出数据计数，并将 data 列作为字符串添加到结果表中count列旁边。

我的SQL查询就像

SELECT t1.user_id, count(t2.id) as c
FROM Table1 t1
INNER JOIN Table2 t2 on t2.user_id = t1.user_id

这将数据列为

+---------+------+
| user_id | c    |
+---------+------+
| 123     | 2    |
| 456     | 1    |
+---------+------+

但是我想要类似的数据

+---------+------+-------------+
| user_id | c    | datas       |
+---------+------+-------------+
| 123     | 2    | abc, xyz    |
| 456     | 1    | pqr         |
+---------+------+-------------+

如何选择用逗号联接的数据？

Answer 1

使用GROUP_CONCAT

SELECT t1.user_id, GROUP_CONCAT(t2.data SEPARATOR ','),count(t2.id) as c
FROM Table1 t1
INNER JOIN Table2 t2 on t2.user_id = t1.user_id
group by t1.user_id

Answer 2

我认为以下想法将与您匹配。

TranslationClass.GetDualTranslation("USA") // Returns US

TranslationClass.GetTripleTranslation("US") // Returns USA