Group By, Having Clause and Order By clause
Download as PPTX, PDF0 likes1,539 views
The document explains SQL concepts including the GROUP BY, HAVING, and ORDER BY clauses, illustrating how to group and filter data from a salary statistics table. It highlights the difference between WHERE and HAVING clauses, noting that WHERE is applied before grouping, and HAVING can filter results based on aggregated values. Additionally, it provides examples of SQL queries to analyze payroll and student results.
Group By, Having Clause and Order By clause
- 1. GROUP BY,HAVING and ORDER BY clause DEEPAM AGGARWAL 1
- 2. org payroll X 1500 Y 3500 Z 3000 GROUP BY Clause SELECT Statement – Grouping Rows Find the payrollof each organization. SELECT org, sum(salary) payroll FROM salary_statistics GROUP BY org Result: salary_statistics emp org salary A X 500 B X 1000 C Y 1000 D Y 2500 E Z 3000 2
- 3. org payroll X 1500 Z 3000 HAVING Clause Find the organizations with payroll less than $3200. SELECT org, sum(salary) payroll FROM salary_statistics GROUP BY org HAVING payroll < 3200 Result: salary_statistics emp org salary A X 500 B X 1000 C Y 1000 D Y 2500 E Z 3000 3
- 4. The Difference Between WHERE and HAVING Clauses WHERE gets processed before any GROUP BY, and so it doesn't have access to aggregated values (that is, the results of min(), max(), etc. functions). HAVING gets processed after GROUP BY and so can be used to constrain the result set to only those with aggregated values that match a certain predicate. Find the organizations with payroll less than $3200. SELECT org, sum(salary) payroll FROM salary_statistics }✗Incorrect WHERE payroll < 3200 GROUP BY org SELECT org, sum(salary) payroll FROM salary_statistics }✓ Correct GROUP BY org HAVING payroll < 3200 4
- 5. SELECT Statement – ORDER BY Clause Find students ordered by merit position. SELECT * FROM result ORDER BY marks DESC result student marks A 25 B 56 C 82 D 25 E 39 5