从另一个视图创建视图

时间:2013-02-12 13:50:37

标签: sql oracle

我在搜索后没有在网上或任何其他资源中找到任何东西,我想知道你是否可以通过加入另一个视图和其他一些表来形成一个视图?与此类似的东西,我想Server_ref.part_notification_view是加入的视图。

Create View "PART_NOTIFICATION_VIEW" ("NOTIFICATION_IX", "PART_NBR", "MFG_CD", "PART_CLASS_CD", "LEADTIME", "BILLTO_CUST_NBR", "BILL_TO_ACCT_NM", "CUST_PART_NBR", "LAST_CUST_PO", "LAST_REQ_DT", "QTY_OPEN", "YEAR_USAGE", "AVAILABLE_SALE_STANDARD_QT", "ISSUE_DATE", "EFFECTIVE_DATE", "BRIEF_DESCRIPTION", "NOTIFICATION_TYPE", "ACTUAL_DOCUMENT_LINK", "AFFECTED_PARTS_LIST_DOC_LINK", "EMAIL_LINK", "FILE_FOLDER", "RECOMMENDED_REPLACEMENT", "PCN_TYPE", "IMPACT", "MANUFACTURER_NM", "LAST_BUY_DT", "LAST_SHIP_DT", "SALES_MIN_BUY_QTY", "SALES_MIN_PKG_QTY", "PART_DESC", "BOND_QOH", "BOND_QIT", "BRANCH_QOH", "BRANCH_QIT", "BOND_QTY", "BOND_PIPELINE", "BOND_OP", "BRAND_CD", "STATUS", "COMMENTS")
AS
  SELECT
    svr.notification_ix,
    svr.part_nbr,
    svr.mfg_cd,
    svr.part_class_cd,
    svr.leadtime,
    svr.billto_cust_nbr,
    svr.bill_to_acct_nm,
    svr.cust_part_nbr,
    svr.last_cust_po,
    svr.last_req_dt,
    svr.qty_open,
    svr.year_usage,
    svr.available_sale_standard_qt,
    svr.issue_date,
    svr.effective_date,
    svr.brief_description,
    svr.notification_type,
    svr.actual_document_link,
    svr.affected_parts_list_doc_link,
    svr.email_link,
    svr.file_folder,
    svr.recommended_replacement,
    svr.pcn_type,
    svr.impact,
    svr.manufacturer_nm,
    svr.last_buy_dt,
    svr.last_ship_dt,
    svr.sales_min_buy_qty,
    svr.sales_min_pkg_qty,
    svr.part_desc,
    NVL(svr.bond_qoh, 0)                                                                    AS bond_qoh,
    NVL(svr.bond_qit, 0)                                                                    AS bond_qit,
    NVL(svr.branch_qoh, 0)                                                                  AS branch_qoh,
    NVL(svr.branch_qit, 0)                                                                  AS branch_qit,
    NVL(svr.bond_qoh, 0)      + NVL(svr.bond_qit, 0) + NVL(svr.branch_qoh, 0) + NVL(svr.branch_qit, 0) AS bond_qty,
    NVL(svr.bond_pipeline, 0) + NVL(svr.po_qt, 0)                                                 AS bond_pipeline,
    svr.bond_op,
    svr.brand_cd,
    cs.status,
    cc.comments
  FROM part_notification_view svr
  JOIN css_status cs
  ON svr.part_nbr = cs.part_nbr
  AND svr.mfg_cd = cs.mfg_cd
  AND svr.billto_cust_nbr = cs.account
  JOIN css_comment cc
  ON svr.part_nbr = cc.part_nbr
  AND svr.mfg_cd = cc.mfg_cd
  AND svr.billto_cust_nbr = cc.account;

2 个答案:

答案 0 :(得分:11)

你当然可以拥有一个建立在另一个视图之上的视图:

create table my_table (id number, name varchar2(20), address varchar2(30));

table MY_TABLE created.

create or replace view my_view_1 as
select id, name
from my_table;

view MY_VIEW_1 created.

create or replace view my_view_2 as
select mv1.id, mv1.name, mt.address
from my_view_1 mv1
join my_table mt on mt.id = mv1.id;

view MY_VIEW_2 created.

但您无法在基础表中引用任何内容,包括不属于视图的任何字段:

create or replace view my_view_3 as
select mv1.id, mv1.name, mv1.address
from my_view_1 mv1
join my_table mt on mt.id = mv1.id;

SQL Error: ORA-00904: "MV1"."ADDRESS": invalid identifier
00904. 00000 -  "%s: invalid identifier"

具有相同列的基础表不是问题,如果在视图中包含多个on,那么无论如何都必须对它们进行别名。

有时可能会遇到性能问题,如果您针对相同的基表创建新视图,并将其展开以包含所需的额外数据,则可能更快,更可靠 - 尽管可能更难维护。

答案 1 :(得分:5)

答案很长......

关系数据库的基本特征之一是表,查询结果和视图(简单存储的查询)之间应该没有逻辑差异。事实上,“关系”是指可通过其中任何一个访问的数据行。 http://en.wikipedia.org/wiki/Relation_%28database%29

当然,不同的RDBMS在不同程度上存在差异,特别是涉及DDL命令(更新,删除,插入)时,它们都对可以应用DDL的对象类型施加限制。

以Oracle为例,系统将允许对密钥保留的视图进行更新和删除,并且插入是可能的,但在实践中很少使用(“而不是”触发器类型可用于允许DDL针对任何视图)。 / p>

所以尽管如此,你可以运行一个选择:

  1. 一张桌子
  2. 一组连接表
  3. 视图
  4. 查询(通常称为内嵌视图)
  5. 加入视图和表格的查询
  6. ...因此可以将选择封装在视图定义中。

    简答:是的