Updating tables in a database
In the indexed-sequential files method, records are physically stored in sequential order on a magnetic disk or other direct access storage device based on the key field of each record.
Each file contains an index that references one or more key fields of each data record to its storage location address.
Any data element can be accessed by moving progressively downward from the root and along the branches of the tree until the desired record is located.2. That is, the network model can access a data element by following one of several paths, because any data element or record can be related to any number of other data elements. Such a database is relatively easy for end users to understand.
Relational databases afford flexibility across the data and are easy to understand and modify.
Direct file organization provides the fastest direct access to records.
When using direct access methods, records do not have to be arranged in any particular sequence on storage media.
Database - is an integrated collection of logically related records or files.
A database consolidates records previously stored in separate files into a common pool of data records that provides data for many applications.
SQL may be used as an independent query language to define the objects in a database, enter the data into the database, and access the data.The data is managed by systems software called database management systems (DBMS).The data stored in a database is independent of the application programs using it and of the types of secondary storage devices on which it is stored.A data model is a method for organizing databases on the logical level, the level of the schema and subschemas.The main concern in such a model is how to represent relationships among database records.
Characteristics of the direct access method include: A database is an organized collection of interrelated data that serves a number of applications in an enterprise.