How to format string in array?

I have the query with various values. Ex:

“data”: [
{
“PID”: “123456”
},
{
“PID”: “1234567”
},
{
“PID”: “12345678”
},
{
“PID”: “123456789”
}
]
},

I need format this value in: [‘123456’, ‘1234567’, ‘12345678’, ‘123456789’]

How to make this?