what is the oracle cursor?

什么是CURSOR，ORACLE的文档作了如下定义：
A cursor is a handle (a name or pointer) for the memory associated with a specific statement. (Oracle Call Interface, OCI, refers to these as statement handles.) Although most Oracle users rely on automatic cursor handling of Oracle utilities, the programmatic interfaces offer application designers more control over cursors.
For example, in precompiler application development, a cursor is a named resource available to a program and can be used specifically to parse SQL statements embedded within the application. Application developers can code an application so it controls the phases of SQL statement execution and thus improves application performance.

An Oracle cursor is a handle to an area in memory that holds the result set of a SQL query, enabling you to individually process the rows in the result set. Oracle uses implicit cursors for all DML statements. Explicit cursors are created and used by application coders.