SQL implementation merges multiple rows of records into one row

SQL Realize merging multiple lines of records into one line

We are in the process of data development , It's a common demand , Is to merge multiple rows into one row , And separated by specific characters .

1、 Before data processing

2, Result data display

3,hive Processing mode

stay hive Inside , use concat_ws Function processing
Format ： concat_ws(‘ Separator ’,collect_set/collect_list( Field ))
Parameter interpretation ：
concat_ws： Merge multiple lines into one line of functions
collect_set： Composite array , The data has been de duplicated
collect_list： Composite array , Data not de duplicated

SQL Script ：
select school,concat_ws(',',collect_set(name)) from student
group by school;

4,MySQL Processing mode

GROUP_CONCAT( Field Separator )
Be careful ：MySQL stay GROUP_CONCAT Function , Weight removal needs to be used distinct keyword , If you need to sort before merging , You can also use order by keyword .

select school,GROUP_CONCAT(name,',') from student
group by school;

I'm meow , If you have problems, please communicate at any time ~~~