Answer simple quiz at the end of the blog post and –
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Aggregates with the Over Clause
You have likely heard the business term “Market Share”. If your company is the biggest and has sold 15 million units in an industry that has sold a total of 50 million units then your company’s market share is 30% (15/50 = .30). Market share represents your number divide by the sum of all other numbers. In JProCo the biggest grant (Ben@Moretechnology.com) is $41,000 and the total of all grants is $193,700. Therefore the Ben grant is 21.6% of the whole set of grants for the company.
The two simple queries in the figure below show all the Grant table records and the sum of the grant amounts.
If we want to show the total amount next to every record of the table – or just one record of the table – SQL Server gives us the same error. It does not find the supporting aggregated language needed to support the SUM( ) aggregate function.
Adding the OVER( ) clause allows us to see the total amount next to each grant. We see 193,700 next to each record in the result set.
The sum of all 10 grants is $193,700. Recall the largest single grant (007) is $41,000. Doing the quick math in our head, we recognize $41,000 is around 1/5 of ~$200,000 and guesstimate that Grant 007 is just over 20% of the total.
Thanks to the OVER clause, there’s no need to guess. We can get the precise percentage. To accomplish this, we will add an expression that does the same math we did in our head. We want the new column to divide each grant amount by $193,700 (the total of all the grants).
By listing the total amount of all grants next to each individual grant, we automatically get a nice reference for how each individual grant compares to the total of all JProCo grants. The new column is added and confirms our prediction that Grant 007 represents just over 21% of all grants.
Notice that the figures in our new column appear as ratios. Percentages are 100 times the size of a ratio. Example: the ratio 0.2116 represents a percentage of 21.16%. Multiplying a ratio by 100 will show the percentage. To finish, give the column a descriptive title, PercentOfTotal.
In today post we examined the basic over clause with an empty set of Parenthesis. The over clause actually have many variations which we will see in tomorrow’s post.
Note: If you want to setup the sample JProCo database on your system you can watch this video. For this post you will want to run the SQLQueriesChapter5.0Setup.sql script from Volume 2.
Question 10
You want to show all fields of the Employee table. You want an additional field called StartDate that shows the first HireDate for all Employees. Which query should you use?
- SELECT *, Min(HireDate) as StartDate FROM Employee
- SELECT *, Max(HireDate) as StartDate FROM Employee
- SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
- SELECT *, Max(HireDate) OVER() as StartDate FROM Employee
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Reference: Pinal Dave (https://blog.sqlauthority.com)
124 Comments. Leave new
Answer 3:
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Country:India
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
As SQl Server does not find the supporting aggregated language needed to support the aggregate function we have to use OVER() to make things understandable to it .
USA
Hi Sir,
The correct answer is option no 3.
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
This option lists out all the employee related information for all the employees and The new column “StartDate” will have the first hire date from the table against each of the employee rows.
1 and 2 option will fail to execute with a error saying
“the first column of the from clause table is invalid in the select list because it is not contained in either an aggregate function or group by clause.”
4th option will give out the latest hire date from the table against each of the employee rows.
So the correct answer is 3 option.
P.Anish Shenoy
INDIA,Bangalore,Karnataka.
Correct option is 3:
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Vairnder Sandhu (India)
Ans is 3
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Partha
India
Corrent anwer is : 3
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
INDIA
Answer is option 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Because,
Option 1 give a error because it is not contained in either an aggregate function or the GROUP BY clause.
Option 2 also give a error as option 1 and moreover it is MAX() function, it will not retrieve joining date.
Option 4 give a MAX date from HireDate column so it will not retrieve joining date.
Thanks,
Country:India
Correct Answer is Option# 3.
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Country: India
Thanks & Regards,
Fazal
Answer: Option 3 is correct
Because we want all the records which are fetched by Select * and Start Date which is fetched by min(Hire Date) but with over()
Country: India
Hello all together!
Option 1 and 2 does not work because of the lack of the over() clause. You will get an error (due to missing group by statement).
Option 4 does work but will return the last hireDate. But that does not match the question since it should be the first hireDate.
Option 3. gives the desired result(s).
Best wishes,
Michael Mikic
from Germany
Correct answer is option 3.
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Paramita Banerjee
country:India
Correct answer :- option 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Min will ensure lowest hire date and Over() will display against each row.
Thanks
Vivek Srivastava
Country: India
Answer is : SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Country : India
Hi,
Correct Answer is:
“SELECT *, Min(HireDate) OVER() as StartDate FROM Employee”
So Option 3 is correct.
Thanks…
Rajneesh Verma
(INDIA)
My answer is option no. 3 because, first two option use aggregate function but not use Group by clause & in fourth option there is Max function is use so it returns with maximum date value of last column. My Country of residence is India.
Correct answer is option 3.
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
(Sale, Nigeria)
3) SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Min Value give u first date Hiredate of Employee and Over() give u from hiredate of employee.
Somnath Desai
India
Correct Ans : 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
If we don’t use Over clause than it will give that group by error as mentioned in your post and for Start Date we have to use Min() function.
Hence, correct answer is 3
Ishan Shah,
Gandhinagar,
India
Answer: Option 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Country: India(sikha)
Correct answer is option 3.
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Jankhana,
India