A PRIMARY KEY constraint automatically has a UNIQUE constraint defined on it. Tr

Question

A PRIMARY KEY constraint automatically has a UNIQUE constraint defined on it.

True

False

Question 18

A unique constraint may contain one null value.

True

False

Question 19

Bring back all employee information for employees whose regions is null.

SELECT *

FROM Employees

WHERE Region Is Null

SELECT *

FROM Employees

WHERE Region = Null

SELECT *

FROM Employees

WHERE Region ''

SELECT *

FROM Employees

WHERE Region IsNull

Question 20

I want a query that returns the first initial of the FirstName and the full LastName of employees concatenated together.

Which of the following queries does this correctly?

SELECT Cast(FirstName,1) + ' ' + LastName
FROM Employees

SELECT LTrim(FirstName,1) + ' ' + LastName
FROM Employees

SELECT First(FirstName,1) + ' ' + LastName
FROM Employees

SELECT Left(FirstName,1) + ' ' + LastName
FROM Employees

Question 21

In the Northwind database, Reports To column in the Employees table can be considered a _____.

Primary Key

Secondary Key

Foreign Key

Candidate Key

Question 22

What is the primary key of the [Order Details] table?

There is no primary key

Order ID and ProductID together

OrderID only

ProductID only

Question 23

What is wrong with the following query?

SELECT  OrderID, ContactName, OrderDate, Freight

FROM Customers INNER JOIN Orders

Nothing is wrong with this query.

The Inner Join is not complete.

Orders needs to be in brackets and it needs an ON statement.

ContactName should be CustomerName.

Question 24

What kind of join is created in the the following query.

SELECT Orders.OrderID , Orders.OrderDate

      , Customers.CompanyName, Orders.Freight

FROM Customers, Orders

inner join

left join

cross join

outer join

Need help ASAP pls! Fast thumbs up! TY

SELECT *

FROM Employees

WHERE Region Is Null

SELECT *

FROM Employees

WHERE Region = Null

SELECT *

FROM Employees

WHERE Region ''

SELECT *

FROM Employees

WHERE Region IsNull

Explanation / Answer

17) A PRIMARY KEY constraint automatically has a UNIQUE constraint defined on it.

--> TRUE

18) A unique constraint may contain one null value

--> TRUE

19)
Option a )
SELECT *
FROM Employees
WHERE Region Is Null

b.Here we can not compare using "=" sign.
c. empty string is different than null
d. isNull doesnt compare with null

20)
option d)
Left function allows us to fetch left sub string.
Here second parameter is 1 , so only substring with 1 character will be returned.

21)
I need to see database to answer this,
but i can guess.
If Northwind and employee both are different table then foreign key is answer.

There is nothing like secondary key.

so you can write foreign key but check database first.

22)
Again i need table . You can comment details about table.

23)
The inner join is not complete.
here "ON" condition is missing on which inner join happens.

24)
Cross join.

Given join is a cross join.

If you have any doubts then you can ask in comment section.
few questions are database related. You can provide me information about tables and i can confirm the answer.

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