Question

我有一个返回下表的查询：

   P_id   S_id   Time
1  "20"     A    15 
2  "30"     B    50
3  "50"     A    99 
4  "70"     A    60

我想基于“ Sid”列对表进行分组，并按“时间”列进行排序，因此它看起来像这样：

        P_id       S_id   
1  "20","70","50"    A     
2       "30"         B

通过更改SQL查询来做到这一点的最佳方法是什么？

尝试仅添加“ GROUP BY S_id”时，出现错误：

SELECT list expression references column query which is neither grouped nor aggregated at [2:16]

（意味着它不知道如何对P_id（所有字符串）的值进行分组

Answer 1

我想你想要

checkedListBox1.SelectedValueChanged -= checkedListBox1_SelectedValueChanged;
checkedListBox1.DataSource = cboxAr;
checkedListBox1.SelectedValueChanged += checkedListBox1_SelectedValueChanged;

如果您希望第一列包含数字，则可以将其添加到：

select s_id, group_concat(p_id order by time) as p_ids
from t
group by s_id;

Answer 2

select group_concat(P_id,',') from tablename group by S_id ;

SQL-按特定字段分组，并合并另一个字段

2 个答案: