DBMS Basics - Interview Questions and Answers

The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language.

This language that enable user to access or manipulate data as organised by appropriate data model.

1. Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
2. Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.

It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.

It executes low-level instruction generated by compiler.

It interprets DDL statements and record them in tables containing metadata.

The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time.