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

本站中文解释

Oracle视图ALL_HIER_COLUMNS是查询关系型数据库系统中层次化数据的特定列的子视图。该子视图提供了有关特定列所支持的层次化查询和特定列所属层次关系的信息。

使用ALL_HIER_COLUMNS可以帮助用户快速地查找层次关系中的列，并确定其可用的层次查询操作，如 BETWEEN、 START WITH 和 CONNECT BY 。它可以用于检查特定列是否支持层次查询，也可以用于构建层次查询句。

官方英文解释

ALL_HIER_COLUMNS describes the columns of the hierarchies accessible to the current user.

Related Views

  • DBA_HIER_COLUMNS describes the columns of all hierarchies in the database.

  • USER_HIER_COLUMNS describes the columns of the hierarchies owned by the current user. This view does not display the OWNER column.

Column Datatype NULL Description

OWNER

VARCHAR2(128)

NOT NULL

Owner of the hierarchy

HIER_NAME

VARCHAR2(128)

NOT NULL

Name of the hierarchy

COLUMN_NAME

VARCHAR2(128)

NOT NULL

Name of the column

ROLE

VARCHAR2(4)
The role the attribute plays in the hierarchy:

  • KEY

  • AKEY

  • HIER

  • PROP

DATA_TYPE

VARCHAR2(106)

Datatype of the column

DATA_LENGTH

NUMBER

NOT NULL

Length of the column (in bytes)

DATA_PRECISION

NUMBER

Decimal precision for the NUMBER datatype; binary precision for the FLOAT datatype, NULL for all other datatypes

DATA_SCALE

NUMBER

Number of digits to the right of the decimal point in a number

NULLABLE

CHAR(1)

Indicates whether a column allows NULL values; the value is N if there is a NOT NULL constraint on the column or if the column is part of a PRIMARY KEY

CHARACTER_SET_NAME

VARCHAR2(44)

Name of the character set:

  • CHAR_CS

  • NCHAR_CS

CHAR_COL_DECL_LENGTH

NUMBER

Declaration length of the character type column

CHAR_USED

VARCHAR2(1)

Indicates that the column uses BYTE length semantics (B) or CHAR length semantics (C), or whether the datatype is not any of the following (NULL):

  • CHAR

  • VARCHAR2

  • NCHAR

  • NVARCHAR2

ORDER_NUM

NUMBER

NOT NULL

Order of the column, with attributes first in the order specified in the definition of the hierarchy followed by hierarchical attributes

ORIGIN_CON_ID

NUMBER

The ID of the container where the data originates. Possible values include:

  • 0: This value is used for rows in non-CDBs. This value is not used for CDBs.

  • n: This value is used for rows containing data that originate in the container with container ID n (n = 1 if the row originates in root).

See Also:

  • “DBA_HIER_COLUMNS”

  • “USER_HIER_COLUMNS”


数据运维技术 » Oracle 视图 ALL_HIER_COLUMNS 官方解释，作用，如何使用详细说明
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