Saturday 21 July 2012

Database concepts-Assignment 1 solutions


Database concepts-Assignment 1


Question 1:
 Provide the create table syntax to Create a Table Employee whose details are as below.
Employee(EmployeeID, LastName, FirstName, Address, DateHired)
Answer:
create table Employee( EmployeeID int(6) primary key,LastName varchar(20),FirstName varchar(20),Address varchar2(50),date date );



Question 2:
Provide the INSERT query to be used in Employee Table to fill the Details.
Answer:
Insert into Employee values( 100,'gourav','kishan','hyderabad',date);



Question 3:
When we give SELECT * FROM EMPLOYEE .How does it Respond?
Answer:
when we type the following query of select * from employee it returns all the data present that is all the columns in employee table. In this case it shows the above values in the insert statement.



Question 4:
Create a Table CLIENT whose details are as below.
Client(ClientID, LastName, FirstName, Balance, EmployeeID)
Answer:
create table Client(ClientID int(6), LastName varchar(20), FirstName varchar(20), Balance float(10) , EmployeeID foreign key references Employee(EmployeeID));
note: incase if we use both emp and client table in 1 db..or has a relation foreign key or not null and references are required else no needed.



Question 5:
Provide the INSERT query to be used in CLIENT Table to fill the Details.
Answer:
INSERT INTO Client(ClientID,LastName,FirstName,Address, EmployeeId) Values (value1,value2,value3,value4 );
We can also use dynamic way to insert values into the table using the '&' operation EX ('& value1','&value2' and so on ... )



Question 6:
When we give SELECT * FROM CLIENT .How does it Respond?
Answer:
 It returns all the rows and columns present in the client table . that is it shows all the field data of client table.



Question 7:
Choose the correct answer. The SQL command to create a table is:
a. Make Table
b. Alter Table
c. Define Table
d. Create Table
Answer : d Create table



Question 8:
Choose the correct answer. The DROP TABLE statement:
a. deletes the table structure only
b. deletes the table structure along with the table data
c. works whether or not referential integrity constraints would be violated
d. is not an SQL statement
Answer : b ( deletes the table structure along with the table data)



Question 9:
What are the different data types available in SQL server?
Answer:
1) Numeric : Stores numeric values.
2) Monetary : It stores numeric values with decimal
places. It is used specially for currency values.
3) Date and Time : It stores date and time information.
4) Character : It supports character based values of
varying lengths.
5) Binary : It stores data in strict binary (0 or 1)
representation.
6) Special purpose: SQL Server contains Complex data
types to handle the XML Documents,Globally unique
identifiers etc.



Question 10:
Which is the subset of SQL commands used to manipulate Oracle Database structures, including tables?
Answer:
DDL( Data Deifinition Language).



Question 11:
 What operator performs pattern matching?
Answer:
LIKE Operator.



Question 12: What operator tests column for the absence of data?
Answer:
 IS NULL Operator.



Question 13:
Which command executes the contents of a specified file?
Answer:
START or @ command.



Question 14:
What is the parameter substitution symbol used with INSERT INTO command?
Answer:
'&' commonly known as ampersand operator.



Question 15: Which command displays the SQL command in the SQL buffer, and then executes it?
Answer: RUN.



Question 16: What are the wildcards used for pattern matching?
Answer:
_ and %
_ = single character substitution .
% = multiple character substitution.



Question 17:
State whether true or false.
EXISTS, SOME, ANY are operators in SQL.
Answer: TRUE.



Question 18:
State whether true or false.
!=, <>, ^= all denote the same operation.
Answer: TRUE.




Question 19:
What are the privileges that can be granted on a table by a user to others?
Answer: Insert, update, delete, select, references, index, execute, alter, all



Question 20:
What command is used to get back the privileges offered by the GRANT command?
Answer: REVOKE.



Question 21:
Which system tables contain information on privileges granted and privileges obtained?
Answer :
USER_TAB_PRIVS_MADE,
USER_TAB_PRIVS_RECD .




Question 22:
 Which system table contains information on constraints on all the tables created?
Answer: USER_CONSTRAINTS.




Question 23: What is the difference between TRUNCATE and DELETE commands?
Answer:
1.Delete is a DML command and Truncate is a
DDL command.
2.Where clause can be used with delete only.
3.THE Delete operation can be rolled back, Truncate operation cant be rolled back again that is it is a permanent delete.



Question 24:
What command is used to create a table by copying the structure of another table?
Answer: CREATE TABLE .. AS SELECT command
Explanation :
To copy only the structure, the WHERE clause of the SELECT command should contain aFALSE statement as in the following.

CREATE TABLE NEWTABLE AS SELECT * FROM EXISTINGTABLE WHERE 1=2;
If the WHERE condition is true, then all the rows or rows satisfying the condition will be copiedto the new table.

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