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

表

ALL_ASSOCIATIONS视图是在Oracle中，系统会维护的一个视图，用于存储外键关联表的信息。对外键进行管理，可以用这个视图来查询，比如查看两个表之间的关联关系，查看某个字段的外键关联情况等。

要使用ALL_ASSOCIATIONS视图，需要通过select语句来查询指定的表或者字段信息，例如可以查询某个表中所有的外键关联信息：

SELECT * FROM ALL_ASSOCIATIONS WHERE TABLE_NAME = ‘表名’;

此外，还可以查看某个列的关联信息：

SELECT * FROM ALL_ASSOCIATIONS WHERE TABLE_NAME = ‘表名’ AND COLUMN_NAME=’列名’;

ALL_ASSOCIATIONS describes user-defined statistics associated with objects accessible to the current user.

Related Views

DBA_ASSOCIATIONS describes all user-defined statistics in the database.
USER_ASSOCIATIONS describes user-defined statistics associated with objects owned by the current user.

Column	Datatype	NULL	Description
`OBJECT_OWNER`	`VARCHAR2(128)`	`NOT NULL`	Owner of the object for which the association is being defined
`OBJECT_NAME`	`VARCHAR2(128)`	`NOT NULL`	Name of the object for which the association is being defined
`COLUMN_NAME`	`VARCHAR2(128)`		Column name in the object for which the association is being defined
`OBJECT_TYPE`	`VARCHAR2(9)`		Kind of object with which statistics are being associated: column, type, package or function, indextype, or domain index.
`STATSTYPE_SCHEMA`	`VARCHAR2(128)`		Owner of the statistics type
`STATSTYPE_NAME`	`VARCHAR2(128)`		Name of statistics type that contains the cost, selectivity or statistics functions
`DEF_SELECTIVITY`	`NUMBER`		Default selectivity of the object, if any
`DEF_CPU_COST`	`NUMBER`		Default CPU cost of the object, if any
`DEF_IO_COST`	`NUMBER`		Default I/O cost of the object, if any
`DEF_NET_COST`	`NUMBER`		Default networking cost of the object, if any
`INTERFACE_VERSION`	`NUMBER`		Identifies the version number of the `ODCIStats` interface. Value is `1` for statistics type implementing Oracle8i 8.1; `0` for types implementing Oracle9i 9.0.0.
`MAINTENANCE_TYPE`	`VARCHAR2(14)`		Specifies whether the object is system-managed or user-managed