Windows batch file - splitting a string to set variables

I feel like I'm going around in circles with FOR loop options.

I'm trying to take a string (output of a command) and split it on commas, then use each value to SET, e.g.

String: `USER=Andy,IP=1.2.3.4,HOSTNAME=foobar,PORT=1234`

So I want to split on comma and then literally use that variable in SET. I don't know ahead of time how many many variables there will be.

I've tried things like:

FOR %%L IN (%MYSTRING%) DO ECHO %%L

but that splits on the equals sign too so I end up with

USER
Andy
IP
1.2.3.4

etc

I just want to be able to do the following so I can `SET USER=Andy` etc, something like:

FOR %%L IN (%MYSTRING%) DO SET %%L

What option or flags am I missing?

In case your input is something like HOSTNAME:PORT and you need to split into separate variables then you can use this

@echo off
set SERVER_HOST_PORT=10.0.2.15:8080


set SERVER_HOST_PORT=%SERVER_HOST_PORT::=,%

for /F "tokens=1* delims=," %%a in ("%SERVER_HOST_PORT%") do (
set SERVER_HOST=%%a
set SERVER_PORT=%%b
)

echo SERVER_HOST=%SERVER_HOST%
echo SERVER_PORT=%SERVER_PORT%

The default delimiters for elements in plain `FOR` command (no `/F` option) are spaces, tab, commas, semicolons and equal signs, and there is no way to modify that, so you may use `FOR /F` command to solve this problem this way:

<!-- language-all: lang-dos -->

@echo off

set MYSTRING=USER=Andy,IP=1.2.3.4,HOSTNAME=foobar,PORT=1234

:nextVar
for /F "tokens=1* delims=," %%a in ("%MYSTRING%") do (
set %%a
set MYSTRING=%%b
)
if defined MYSTRING goto nextVar
echo USER=%USER%, IP=%IP%, HOSTNAME=%HOSTNAME%, PORT=%PORT%

Another way to solve this problem is first taking the variable name and then executing the assignment for each pair of values in a regular FOR command:

setlocal EnableDelayedExpansion

set MYSTRING=USER=Andy,IP=1.2.3.4,HOSTNAME=foobar,PORT=1234

set varName=
for %%a in (%MYSTRING%) do (
if not defined varName (
set varName=%%a
) else (
set !varName!=%%a
set varName=
)
)
echo USER=%USER%, IP=%IP%, HOSTNAME=%HOSTNAME%, PORT=%PORT%

**EDIT 2023/01/20:** _New method added_

I know this is a very old question. However, I can't resist the temptation to post a new _very interesting_ method to solve this old problem:

@echo off

set MYSTRING=USER=Andy,IP=1.2.3.4,HOSTNAME=foobar,PORT=1234

set "%MYSTRING:,=" & set "%"

echo USER=%USER%, IP=%IP%, HOSTNAME=%HOSTNAME%, PORT=%PORT%

If you want to know where the magic is, remove the `@echo off` line, execute the program and carefully review the screen...