Understanding acronyms DSL, DML, DCL, and DDL
Question: Explain the acronyms DSL, DML, DCL, and DDL. How are they all related?
DSL or data sublanguage is the language that mainly deals with database objects and operations. Following are the examples of industry standard DSLs:
⒜ SQL (structured query language)
⒝ QUEL and
⒞ KQL (knowledge query language)
The DSL data sublanguage consists of following components:
① data definition language (DDL)
② data manipulation language (DML)
③ data control language (DCL)
DDL, DML and DCL are not independent entities but are integral part of a single coherent DBMS product.
Question: What are the components of DBMS Suite?
Answer: The essential Components of DBMS Suite are:
• DBMS Engine
• Data Definition Subsystem
• User Interface Subsystem
• Application Development Subsystem
• Data Administration Subsystem
• Data Dictionary Subsystem
• Data Communications Manager
• Utilities Subsystem
Question: What is data redundancy? What is its impact on database system?
Answer: Data redundancy refers to condition when the same data is stored unnecessarily at different places. It often leads to chaos in managing and updating data.
Following are the pitfalls if the data is redundant:
① Data-entry Errors: It becomes cumbersome to enter data and update at various places.
② Data inconsistency: Data is redundant at various places, there are chances that data is not being updated consistently.
③ Data Security Issues: It becomes a challenging task to implement data security. There are chances that there can be unauthorized data access.
④ Data Management Anomalies: Redundant data often leads to various anomalies when data is being deleted or updated or inserted. It also leads to data integrity issues.