Here is an example of a business analyst cover letter.
A cover letter should be short, specific and no longer than one page. You should specify your career objectives in relation to the position, what appeals to you about the job and a short summary of your experience and skills.
It is no longer mandatory to send a traditional cover letter along with your CV. Do so only if it is required or you consider it to be relevant. Most of the time, sending an e-mail with your CV as an attachment is fine. The body of your e-mail does duty as a short, informal cover letter.