This is the DBMS questions and answers section on "SQL Basics" with explanation for various interview, competitive examination and entrance test. Solved examples with detailed answer description, explanation are given and it would be easy to understand.
1. Which one of the following is used to define the structure of the relation ,deleting relations and relating schemas ?
- A. DML(Data Manipulation Langauge)
- B. DDL(Data Definition Langauge)
- C. Query
- D. Relational Schema
Answer: Option B
Explanation:
DDL(Data Definition Langauge)
Data Definition language is the language which performs all the operation in defining structure of relation.
2. Which one of the following provides the ability to query information from the database and to insert tuples into, delete tuples from, and modify tuples in the database ?
- A. DML(Data Manipulation Langauge)
- B. DDL(Data Definition Langauge)
- C. Query
- D. Relational Schema
Answer: Option A
Explanation:
DML(Data Manipulation Langauge)
DML performs change in the values of the relation .
3. Create table employee (name varchar ,id integer) What type of statement is this ?
- A. DML
- B. DDL
- C. View
- D. Integrity constraint
Answer: Option B
Explanation:
DDL
Data Definition language is the language which performs all the operation in defining structure of relation.
4. Select * from employee
What type of statement is this?
- A. DML
- B. DDL
- C. View
- D. Integrity constraint
Answer: Option A
Explanation:
DML
Select operation just shows the required fields of the relation. So it forms a DML
5. The basic data type char(n) is a _____ length character string and varchar(n) is _____ length character.
- A. Fixed, equal
- B. Equal, variable
- C. Fixed, variable
- D. Variable, equal
Answer: Option C
Explanation:
Fixed, variable
Varchar changes its length accordingly whereas char has a specific length which has to be filled by either letters or spaces .
