Database for Libraries -2

1) BOOKS AND PERIODICALS (HOUSE KEEPING OPERATIONS)
- How many books/ articles are available of particular author.
- How many copies / titles/ articles are available on particular subject.
- How many copies of particular author and particular title are available.
- How many books are issued to a particular user and what is his due date.
- The particular book issued to whom and when and so on.
  Similarly regarding all types of library materials any users and library staff can have cross checks and bibliographical helps and gets its results or answers in very short time which is not always and possible with manual system. Thus the library database is a very useful and time saving tool for Library user and library staff as well.
The figure No. 1 may be useful in understanding DBMS System of a library.
Each data elements is stored once and only once in a record any numbers of users can have access to a data elements any numbers of times. Further data elements in the database are independent of data representation, devices, descriptions, programs and thus a database is physically available object.
The database can have various physically files such as:
a) Sequential files,
b) Inverted files,
c) Indexed sequential files,
d) Chained files,
e) Tree structured files.
The typical operations which are performed on database are
1. Inserting a record or adding a record.
2. Deleting a record.
3. Editing or modifying a record
4. Searching a record by any field as Acc. No., key word, Author, Title, Publisher, Date of purchase, Year of publication, etc.
If we look at any information system we may find that on information system is self sufficient. Today the databases are known as a major source of information. Most of the printed indexing and abstracting services are available in the form of machine readable database such as MEDLARS [Index wedicus], INSPEC[Science abstract], CAS[Chemical Abstract], Agris[Metal Abstract], INIS[International Nuclear Information system], Agris[international information system for agriculture science and technology] etc.
DATA MODELS
Following are the four important data models:
1. Entity- Relationship model,
2. Relational Model,
3. Network Data Model.
We will see now in detail regarding this data models.
1. Entity - Relational Model :- The Entity relationship data model is based on a perception of real word which consists of set of basic object called entities and relationship among those object. An entity is on object that exists and is distinguishable from other objects and an entity is a set of entities of same type. An entity is represented by a set of attributes of the library users are name, department, designation and address. Possible attributes of a collection entity seat are Acc. No., Author, Title and keyword. For each attributes there is a set of permitted value, called the domain of the attribute. The domain attribute name might be set of all text strings of certain length. In same way the domain of attribute number might be set of all positive integers.