Clickhouse pit filling note 2: the join condition does not support non equal judgments such as greater than and less than

I have a problem recently ,ClickHouse There is a table in , There is a user in it (f_user) Field , There are statistics every day , Now I want to get some new user data generated , Because I'm used to MySQL, I naturally want to make one with the same table Join operation , Then the date of the previous table is greater than that of the next table ,where In filter condition , The date in the following table is null, So you can get the data , But it turns out ClickHouse This operation is not supported , For a long time , Finally, this problem is solved , Here is a detailed description of the process .

• Problem description

stay MySQL in , It can often be written in a way similar to the following ：

Select a.f_date,count(a.f_user) from t_table a 
left join t_table b on a.f_date>b.f_date and a.f_user=b.f_user
Where b.f_date is null 
 Group by a.f_date

It's written in MySQL useful , But in ClickHouse Inside , The following exceptions will be reported ：

ClickHouse exception, code: 48, host: 128.0.0.1, port: 1166