Dbms table related questions
Answers
1) Define Database.
Answer: A prearranged collection of figures known as data is called database.
2) What is DBMS?
Answer: Database Management Systems (DBMS) are applications designed especially which enable user interaction with other applications.
3) What are the various kinds of interactions catered by DBMS?
Answer: The various kind of interactions catered by DBMS are:
Data definition
Update
Retrieval
Administration
4) Segregate database technology's development.
Answer: The development of database technology is divided into:
Structure or data model
Navigational model
SQL/ relational model
5) Who proposed the relational model?
Answer: Edgar F. Codd proposed the relational model in 1970.
6) What are the features of Database language?
Answer: A database language may also incorporate features like:
DBMS-specific Configuration and management of storage engine
Computations to modification of query results by computations, like summing, counting, averaging, grouping, sorting and cross-referencing Constraint enforcement Application Programming Interface
7) What do database languages do?
Answer: As special-purpose languages, they have:
Data definition language
Data manipulation language
Query language
8) Define database model.
Answer: A data model determining fundamentally how data can be stored, manipulated and organised and the structure of the database logically is called database model.
9) What is SQL?
Answer: Structured Query Language (SQL) being ANSI standard language updates database and commands for accessing.
10) Enlist the various relationships of database.
Answer: The various relationships of database are:
One-to-one: Single table having drawn relationship with another table having similar kind of columns.
One-to-many: Two tables having primary and foreign key relation.
Many-to-many: Junction table having many tables related to many tables.
11) Define Normalization.
Answer: Organized data void of inconsistent dependency and redundancy within a database is called normalization.
12) Enlist the advantages of normalizing database.
Answer: Advantages of normalizing database are:
No duplicate entries
Saves storage space
Boasts the query performances.
13) Define Denormalization.
Answer: Boosting up database performance, adding of redundant data which in turn helps rid of complex data is called denormalization.
14) Define DDL and DML.
Answer: Managing properties and attributes of database is called Data Definition Language(DDL).
Manipulating data in a database such as inserting, updating, deleting is defined as Data Manipulation Language. (DML)
15) Enlist some commands of DDL.
Answer: They are:
CREATE:
Create is used in the CREATE TABLE statement. Syntax is:
CREATE TABLE [column name] ( [column definitions] ) [ table parameters]
ALTER:
It helps in modification of an existing object of database. Its syntax is:
ALTER objecttype objectname parameters.
DROP:
It destroys an existing database, index, table or view. Its syntax is:
DROP objecttype objectname.
16) Define Union All operator and Union.
Answer: Full recordings of two tables is Union All operator.A distinct recording of two tables is Union.
17) Define cursor.
Answer: A database object which helps in manipulating data row by row representing a result set is called cursor.
18) Enlist the cursor types.
Answer: They are:
Dynamic: it reflects changes while scrolling.
Static: doesn't reflect changes while scrolling and works on recording of snapshot.
Keyset: data modification without reflection of new data is seen.
19) Enlist the types of cursor.
Answer: They types of cursor are:
Implicit cursor: Declared automatically as soon as the execution of SQL takes place without the awareness of the user.
Explicit cursor: Defined by PL/ SQL which handles query in more than one row.
20) Define sub-query.
Answer: A query contained by a query is called Sub-query.
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