We have started working with functions to manipulate strings.

    SELECT phone AS original_phone,  -- from `8005551205` to `(800) 555-1205`
      LEFT(phone, 3) AS area_code,  -- extracting `800`
      SUBSTRING(phone, 4, 3) AS branch_exchange,  -- extracting `555`
      RIGHT(phone, 4) AS subscriber_number,  -- extracting `1205`
      CONCAT (  -- concatenating values 1 to 6
        `(`,  -- value 1, hard-coded the opening parenthesis
          LEFT(phone, 3),  -- value 2, area code from `phone`
          `) `,  -- value 3, hard-coded closing parenthesis + space
        SUBSTRING(phone, 4, 3),  -- value 4, branch from `phone`
        ` - `,  -- value 5, hard-coded hyphen
        RIGHT(phone, 4)  -- value 6, subscriber number from `phone`
        ) AS legible_phone
    FROM table1;

Download the class notes for day 3.