For each loop multiple objects in arrays


I need to process a command on mac addresses i have pulled from a database but am unsure how to craft a loop in the correct manner. I need to execute a command below on each mac pulled from this query. Any help would be great.

"command": "blockClient",
"mac": "machere"

Send the array to a split node, then a change node which SETs msg.payload.command to a string of blockClient