使用php将电子邮件发送到从数据库检索的电子邮件地址

I have a column (named user_email) in a table called (event) in my database, This column has email addresses. I want to get all these email addresses and send one email for all of them. I tried to use 'for'loop but it only sends the email to one email only, I might be using for in a wrong way, any suggestion, I have a column (named user_email) in a table c