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:
Statistical charts with numerical information play an important role on Internet web pages. In addition to the basic function of displaying numbers, people now pay more and more attention to the beauty and interactivity of these charts. As a result, programmers are facing more and more serious challenges. The process that most people imagine using drawing software to generate pictures and then putting them on web pages is unrealistic.
Correlation analysis is one of the important components in the data mining system, and its representative case is "shopping basket analysis". Let's take the shopping basket analysis data provided by the data mining software Clementine as an example to explore this aspect from multiple aspects.
