Subquery execution

[Tremaine Buchanan]

Hi, I'm trying to conduct a subquery however I'm getting the following error:

{

  "code": "ER_BAD_FIELD_ERROR",

  "errno": 1054,

  "sqlState": "42S22",

  "index": 0

}

This is the query: 'SELECT id, first_name, last_name, docs = (SELECT COUNT(id) FROM documents WHERE employee_id = employees.id ) FROM employees'.

The column 'docs' doesn't exist in the table employees. I would like to compute this field based on the count of documents from the documents table.