ErrCode with "Select Into Outfile with a variable" - Confusing Permissions - mysql

Question

Background: I work with phpMyAdmin (MySQL Workbench) in a mysql DB. I write some PHP code to import data in the DB and execute this with the task scheduler of windows. <= this works fine!
Now I want to export some data into a file in a Windows folder. At first I write the SQL code in phpMyAdmin to see some debug-infos. <= this is where the problem occurs.
My Topic:
I want to export some columns of my DB. My Goal is to put a variable CURRENT_TIMESTAMP in the filename. For this I use the Concat statement.
My code (posted below), gets the result of the following error:
Can't create/write to file 'C:\Temp\Export\2018-08-08 09:21:27.txt' (Errcode: 13 "Permission denied")
Funny thing is, if I replace the variable CURRENT_TIMESTAMP with e.g. "Hello World" there is no error and my file is created in the folder.
Here is my code:
*set #sql = concat("SELECT `LS_ID_Nr`,
`Stk_pro_Krt_DL` * `Krt_DL` + `RB_Stk_pro_Krt_DL` * `RB_Krt_DL`,
`Umstellzeit`,
`Produktionszeit`,
`Teilmeldung`,
`Fertigmeldung` INTO OUTFILE 'C:/Temp/Export/",CURRENT_TIMESTAMP,".txt' fields terminated by ';' lines terminated by '\r\n' From praemie where Proof_P = 0");
prepare s1 from #sql;
execute s1;
DROP PREPARE s1;
UPDATE praemie SET Proof_P = 1 WHERE Proof_P = 0;*
Does anybody have an idea why there is an Permission Error with the use of a variable? Thanks in advance!

Answer 1

Ooooohh....
I get it now!
The problem is, that windows not handle ":" in filenames. So I have to edit the code with the Date_Format statement like this:
set #sql =
concat("SELECT `LS_ID_Nr`, `Stk_pro_Krt_DL` * `Krt_DL` + `RB_Stk_pro_Krt_DL` * `RB_Krt_DL`,
`Umstellzeit`, `Produktionszeit`, `Teilmeldung`, `Fertigmeldung`
INTO OUTFILE 'C:/Temp/Export/Test - ", DATE_FORMAT(NOW(), '%Y%m%d%H%i%s')," - Test.txt'
fields terminated by ';'
lines terminated by '\r\n'
From praemie where Proof_P = 0")