选择2列并合并数据 [英] Select 2 column and merge data

问题描述

我想在col1中合并相同的值，并在col2中合并特定的数据，并将其显示在html表中.我的sql表看起来像这样

I want to merge the same value in col1 and with there specific data in col2 and display it in html table. My sql table looks like this

+------+------+
|col1  |col2  |
+------+------+
|1     |test  |
+------+------+
|2     |test1 |
+------+------+
|1     |test2 |
+------+------+
|1     |test4 |
+------+------+
|2     |test8 |
+------+------+

预期结果显示在html表中，如下所示.

The expected result is displayed in html table like this.

+------+------+
|      |test  |
|      |      |
|  1   |test1 |
|      |      |
|      |test2 |
+------+------+
|      |test4 |
|  2   |      |
|      |test8 |
+------+------+

推荐答案

您的示例数据不是明确的，但是您可能正在寻找GROUP_CONCAT:

Your sample data is not explicit, but you might be looking for GROUP_CONCAT:

SELECT 
    col1,
    GROUP_CONCAT(col2 SEPARATOR '\n') col2
FROM mytable 
GROUP BY col1
ORDER BY col1

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