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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 is 3.
Since the first date is required so Min and among all data is required so Over().
Mehul Gardi
India
Answer is option 3
First date is required so MIN and among all data so OVER()
this should be the answer from the list of choices:
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Ritesh (India)
Correct Answer option is 3
3.SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Regards
prasad yangamuni
india
Hi Pinal,
None of the options seems to be Correct Answer for this question.
i think the option – 3 will works for this question, but it is returning the Minimum date from the HireDate column as the StartDate for all employees.
I think this is not Correct Answer.
Please Correct me if i am wrong.
Thanks,
Narendra(India).
The Correct Answer is : 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Answer: Option 3.
Explanation:
* Select *, will returns all Employee records
* Min(HireDate) OVER() as StartDate, returns Min(HireDate) i.e. First Date
OVER() which is according to employee id.
example : tblEmployee(Id,Name,Address,HireDate)
3. SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
ghanshyam
bangalore
Option 3 is the correct answer
3. SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
City : Baroda
Country: India
Thanks
GurjitSingh
Option 3
Country : India
The correct answer is option 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
as we want to show first hiredate, which can be calculated using MIN() function
and Over() clause will print it for all the records
from:
Malay shah
City:Ahmedabad
Country:India
correct option
3) SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
Because min() shows the minimum value of the column provided. if there is no aggregation provided so we will use OVer()
Country-India
Hi,
Correct Ans is
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.
City:Ahmedabad
Country: India
correct Option is 3 .
Minimum of Hiredate will be first hire date,as there is no group by clause, 1) is invalid. 3) with over() clause will put the earliest hire date in each row.
Shilpa
India
The correct answer is option 3
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
INDIA
Brijesh
Correct answer: #3 (SELECT *, Min(HireDate) OVER() as StartDate FROM Employee)
Country of residence: India
I would like to mention to all readers that the OVER clause is magical, and once you start using it, you get addicted to it :)
Option 3 is valid in this case.
Correct Answer is Option 3:
OVER gives us ability to get minimum HireDate along with other columns.
Option 1 and 2, are not going to work, as we need all aggregate values
Option 4 is giving us LATEST HireDate
Country: INDIA
Correct Answer:
1. SELECT *, Min(HireDate) as StartDate FROM Employee
– This query give an error as (invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause..)
2. SELECT *, Max(HireDate) as StartDate FROM Employee
– This query give an error as (invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause..)
3. SELECT *, Min(HireDate) OVER() as StartDate FROM Employee
– This query executes successfully.
4. SELECT *, Max(HireDate) OVER() as StartDate FROM Employee
– This query executes successfully, but it results as the maximum(latest) date of the employee joined.
Country: India
Correct answer is
SELECT *, Min(HireDate) OVER() as StartDate FROM Employee