Oracle 视图 ALL_EVALUATION_CONTEXT_VARS 官方解释，作用，如何使用详细说明

网络编程 Oracle 视图 ALL_EVALUATION_CONTEXT_VARS 官方解释，作用，如何使用详细说明 10-17

ALL_EVALUATION_CONTEXT_VARS 视图显示当前模式下定义的评估上下文变量（也用于Oracle Data Mining）。该视图允许用户查看和维护评估上下文变量。

要使用 ALL_EVALUATION_CONTEXT_VARS 视图，首先需要创建一个评估上下文：

CREATE EDGE VIEW customers AS SELECT * FROM customer;

之后，就可以使用 ALL_EVALUATION_CONTEXT_VARS 视图，如下所示：

SELECT VARNAME, VARTYPE, VARVALUE
FROM ALL_EVALUATION_CONTEXT_VARS
WHERE CONTEXT_NAME = ‘CUSTOMERS’;

此查询将返回与指定评估上下文相关的变量信息，诸如变量名称、类型和值。

ALL_EVALUATION_CONTEXT_VARS describes the variables in the rule evaluation contexts accessible to the current user.

Related Views

DBA_EVALUATION_CONTEXT_VARS describes the variables in all rule evaluation contexts in the database.
USER_EVALUATION_CONTEXT_VARS describes the variables in the rule evaluation contexts owned by the current user. This view does not display the EVALUATION_CONTEXT_OWNER column.

Column	Datatype	NULL	Description
`EVALUATION_CONTEXT_OWNER`	`VARCHAR2(128)`	`NOT NULL`	Owner of the evaluation context
`EVALUATION_CONTEXT_NAME`	`VARCHAR2(128)`	`NOT NULL`	Name of the evaluation context
`VARIABLE_NAME`	`VARCHAR2(128)`		Name of a variable in the evaluation context
`VARIABLE_TYPE`	`VARCHAR2(4000)`		Datatype of the variable
`VARIABLE_VALUE_FUNCTION`	`VARCHAR2(4000)`		Function used to retrieve the value of the variable; NULL for variables that are not implicit
`VARIABLE_METHOD_FUNCTION`	`VARCHAR2(228)`		Function used to retrieve the result of method invocation on the variable. Such a function can speed up evaluation, if there are many simple rules that invoke the method on the variable.

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