Sybase IQ supports three levels of variables:
Local variables These are defined inside a compound statement in a procedure or batch using the DECLARE statement. They exist only inside the compound statement.
Connection-level variables These are defined with a CREATE VARIABLE statement. They belong to the current connection, and disappear when you disconnect from the database or when you use the DROP VARIABLE statement.
Global variables These are variables that have system-supplied values.
Local and connection-level variables are declared by the user, and can be used in procedures or in batches of SQL statements to hold information. Global variables are system-supplied variables that provide system-supplied values. All global variables have names beginning with two @ signs. For example, the global variable @@version has a value that is the current version number of the database server. Users cannot define global variables.
