This the sis addresses the effect of the database semantic migration on an
application program and deals with the conversion process of queries
written for processing the database. Semantic migration to be considered
in this study, which often results from the natural growth of an
enterprise, includes the addition
types, the addition
association, the addition
entity types, the addition
addtition
attribute migration, and entity-type contraction. Among the above database
changes, addition operation will not affect the query because the added
information can be ingnored in the external schema with which the query
interact. Other operations may affect application programs in various
ways. The conversion of host language program which requires detailed
analysis of host language sequence is not the concern of this study. This
investigation is limited to the coversion are based on database semantics.
The semantics of both the source and target database are described in
terms of entity types and their associations. A data translation language
DSML is designed for database semantic migration which explicitly
describes the semantic changes of database. The semantics of a query is
represented by a number of standardized access paths which represent the
general access patterns associated with entity types and their
associations. Program conversion is achieved by meaning-preserving
transformations of the standardized access paths to account for the
various types of database semantic migration.
本論文主要是討論資料庫意義改變時應用程式所受之影其修改的方法。本研究所 討論
之資料庫意義改變是為使用此資料庫之機構的自然成長所引起者。它包括增加或 消減
一事項之敘述，增加或消減一關聯之特性敘述，增君或消減事項，增加或消減關 聯，
改變一關聯之種類，特性敘述變為獨立事項以及獨立事項變為一事項或關聯之特 性敘
述。因為增加的資料在次模式描述中可以略去，因此在上述的資料庫改變中，“ 增加
”的改變不會影響到應用程式。至於其他種類的改變則對慹用程式會有不同形式 的影
響。某些影響將會涉及主語言部份，但主語言部份的修改需要詳細的主語言程式 分析
，這個工作不在本論文討論範圍之內。本論文討論者為資料詢訊部份之分析及修 改方
法。詢訊庂分析及修改方法均基於資料庫之意義。改變前及改變後之資料庫意義 是以
其所包含之事項及關聯來描述。資料庫的改變是由資料意義轉換語言來表示，此 種轉
換語言可將資料庫意義改變清楚的描述。詢訊則用標準化擷取路徑來表示。一個 標準
化擷取路徑為單位，設計修改的方法。將每個受到資料庫意義改變影響之標準化 擷取
路徑修改之後，應用程式之修改乃得以完成。

deletion of attributes to
deletion of descriptive attributes to
deletion of descriptive attributes to
deletion of entity types, the
deletion of associations, the change of an association type,