加密要存储在mysql数据库中的文本的最佳方法

I want to know the best way of storing text in a database and encrypting it so as to prevent others (admin) from reading it. I'm allowing users to write (up-to) paragraphs of plain text and then storing in a database. This text is then displayed back to the user in their account. This means that I will have to be able to decrypt the data once i've encrypt it and stored it in the database. (I have created the project using PHP)I want to know the best way of storing text in