Mysql – Creating a thesql trigger without hard-coding database name

I assume new.follower_id is supposed to be:

select follower_id from folow where circle_id=new.circle_id;

I don't think this will work. If you want to use this approach you need to declare a variable for follower_id and select into that. However, a better approach (IMO) is to do:

INSERT INTO activity( uid, performed_activity_id, activity_type_id ) 
    VALUES (new.uid, new.event_id,  '1');

insert into notification_table (sender_id,object_id,receiver_id)
    select new.uid ,new.event_id, follower_id 
    from folow where circle_id=new.circle_id;

There is no way to do this with MySQL own tools. If you look closer it makes sense that you have to create your table first, you have to specify datatypes for the fields of your csv file, possible indexes and so on. MySQL can´t predict which datatype you want to use, so here is some manual work to do.

On the other hand you can use external scripts to archive what you want, a quick and dirty example would be:

#!/bin/bash
# create table for import
head -1 test.csv | awk '{split($0,f,","); printf "create table test (%s INT, %s VARCHAR(50));",f[1],f[2]}' | mysql -u USER -pPASS SCHEMA
# import csv
mysql -uUSER -pPASS SCHEMA -e "LOAD DATA LOCAL INFILE 'test.csv' INTO TABLE testcsv FIELDS TERMINATED BY ',' ENCLOSED BY '\"' LINES TERMINATED BY '\n' IGNORE 1 LINES"

Above "script" lefts plenty of room for optimization, it should only give you a basic idea how to archive what you need with common Linux tools.