在MySQL中加密/解密大文本数据的推荐方法是什么？

I have a client/server application that runs on an intranet, and I have the requirement to encrypt the data in one field of one table of the database. That field is currently TEXT data type, which I have learned is not good for encryption in MySQL. The text stored in the field is similar to an employee performance evaluation containing narrative comments from supervisors. Because of personal information restrictions concerning the network the system runs on, this data cannot be stored in plain text. The data also needs to editable by different users with differ "roles" (authentication levels) via the client side of the application.I have a client/server application that runs on