[大数据]mysql数据行转列，列转行

行转列

使用union，一行变多行

select temp.uid, temp.column
from (
    select uid, column1 as column
    from base_table
    
    union 
    select uid, column2 as column
    from base_table
) temp

列转行

select temp.uid,
       temp.column1 as column1,
       temp.column2 as column2
from (
	select uid,
           sum(if(条件1, 1, 0)) as column1,
           sum(if(条件2, 1, 0)) as column2 
           from base_table
           group by uid
	) temp