16.2. User Variable Properties

In MySQL 5, user variable names are not case sensitive. (They are case sensitive before MySQL 5.)

User variables are specific to the client connection within which they are used and exist only for the duration of that connection. A user variable used within a connection cannot be accessed by other connections. When a connection ends, all its user variables are lost.

A user variable that has been assigned a non-binary string value has the same character set and collation as the string. All user variables have an implicit coercibility value.