What is basic SELECT statement?

SELECT Statement A SELECT statement retrieves data from the database. With SELECT statement PROJECTION, SELECTION and JOIN can be performed on database tables. As data in relational database is stored in TABLES. TABLE has ROW and COLUMN structure. With SELECT statement all rows and all columns can be retrieved, this is known as PROJECTION. But, if rows and columns are retrieved on the basis of some condition, it is known as SELECTION. And suppose if some information is needed and that is stored in two or more different tables but are related, use JOINS to retrieve it from two or more tables. In SQL, basic SELECT statements are as follows: SELECT  * FROM  [ table_name ] ; SELECT   [ column1 ] ,  [ column2 ] ,  [ column3 ] ,   .....   FROM   [ table_name ] ; SELECT and FROM are known as clauses.  SELECT clause allows to specify columns to be selected from the database table.  FROM clause allows to specify table name that has those column to be s

What are the different types of database users?

Following are the types of database users:

1) Application Programmer:  
A technical person who writes database application programs. They are also known as Software Developer or Software Engineer. They write programs by using computer programming languages and development tools.

Languages: Java, COBOL, PASAL, PL/SQL etc are used.
Development tools: Eclipse, JDeveloper, SQL Developer etc are used.

Application programs that interact with database are developed as per the user requirements and include functionalities of creating, reading, updating and deleting data from the database. These are commonly known as CRUD operations.  

2) Naive Users:
Naive users use application programs written by application programmer for interacting with  the database. These users don't have much knowledge about database but thy use predefined applications to access required data from the database. 

Clerk working at the LIC office to maintain customer policy data is a naive user.
Student filling information for online university registration is a naive user.
Operator doing a railway reservation is a naive user.

3) Sophisticated users:
These users interact with database by using some query language or by some analytical tool. System Analyst or Data Analyst are sophisticated users. Commonly use SQL and MS Excel for data analysis.

4) Specialized Users :
These are scientist or engineers who can create their own application programs for some specific needs and is different from the programs written by application programmers. They are comfortably familiar with database systems.

5) Database Administrator:
Also know as DBA. They perform the complete administration of database systems.


Post a Comment

Popular posts from this blog

Define the terms: domain, tuple, attribute and relation

With the help of block diagram explain the architecture of a DBMS.