I have created the following procedure that using two different prepared statements, writes some data in a text file with the same name.
PROCEDURE
delimiter !!
drop procedure if exists copyIntoFile !!
create procedure copyIntoFile()
begin
declare path varchar(255);
set path = concat("'C:/ProgramData/MySQL/MySQL Server 5.7/Uploads/", curdate(), ".txt'");
set @aux1 = concat("select * from movie_modification where modified = true into outfile ", path,
" fields terminated by ';' lines starting by 'Edit: ' terminated by '\n';");
prepare stmt1 from @aux1;
execute stmt1;
deallocate prepare stmt1;
set @aux2 = concat("select * from movie_modification where modified = false into outfile ", path,
" fields terminated by ';' lines starting by 'New: ' terminated by '\n';");
prepare stmt2 from @aux2;
execute stmt2;
deallocate prepare stmt2;
delete from movie_modification;
end !!
delimiter ;
When I executed this procedure, statement aux1 executes correctly and creates the text file and writes the data in it. But when the execution goes to the second statement (aux2), I get the following error:
Error Code: 1086. File 'C:/ProgramData/MySQL/MySQL Server 5.7/Uploads/2020-04-03.txt' already exists
This error occurs because the file is already being created in statement aux1.
How can I modify then the second statement aux2 knowing the file it's already been created?
I dont think you can ask MySQL to append to the same file, but you could UNION the 2 queries.
You can add the 'Edit: ' and 'New: ' into the query, therefore allowing you to use a UNION to reduce this to one query.
You may have to change your query to specify all the columns you want a SELECT 'Edit: ',* wont work, but here is a suggestion.
delimiter !!
drop procedure if exists copyIntoFile !!
create procedure copyIntoFile()
begin
declare path varchar(255);
set path = concat("'C:/ProgramData/MySQL/MySQL Server 5.7/Uploads/", curdate(), ".txt'");
set @aux = concat("select 'Edit: ', col1,col2 from movie_modification where modified = true
UNION ALL
select 'New: ', col1,col2 from movie_modification where modified = false
into outfile ", path,
" fields terminated by ';' lines terminated by '\n';");
prepare stmt from @aux;
execute stmt;
deallocate prepare stmt;
delete from movie_modification;
end !!
delimiter ;