The sample data source format is as follows. Now we need to count the number of people with uid in each group:
By default when using a pivot table, you can only select "Count" to get the number of rows for each group, and the uid is not deduplicated;
The group_concat function in MySQL can combine the specified fields of the group into one row of content, which is more suitable for column conversion.
The complete syntax is as follows:
group_concat([DISTINCT] Field to be concatenated [Order BY ASC/DESC sorting field] [Separator 'separator'])
The default delimiter is comma
Example:
select id,group_concat(distinct name) from table group by id;
It should be noted that there is a default limit on the length of the merged fields.
refer to:
