column-level encryption

Column-level encryption is a method of database encryption in which the information in every cell (or data field) in a particular column has the same password for access, reading, and writing purposes. 

Column-level encryption is not the only method for database encryption. Other methods include:

• Row-level encryption, in which each row has a unique password for all of its cells.
• Cell-level encryption, in which each individual cell has its own unique password.
• Tablespace-level encryption, in which each tablespace has a unique password for all of its contents.
• File-level encryption, in which individual files are encrypted in blocks according to predetermined criteria.

Advantages of column-level encryption, relative to other encryption methods, include widespread use (so most database administrators are familiar with it), and the ability to simultaneously protect columns in databases that exist in different platforms. Disadvantages include reduced or limited available query optimization functions, increased data file size, increased demands on system resources, and an increased number of potential security holes (because more frequent changes must be made on a continuing basis).