For each loop multiple objects in arrays

Hello,

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