over() and over(partition by xyz)

Author: mayankSystems

src/main/java/dev/mayankg/db_concepts/mysql/exc06/window_funcs.sql

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+-- VIEW ALL RECORDS
+SELECT * FROM employees;
+
+-- MIN and MAX salary from the employees table
+SELECT
+	AVG(salary) AS avg_salary,
+    MIN(salary) AS min_salary,
+    MAX(salary) AS max_salary
+FROM employees;
+
+-- SHOW EMPLOYEE DETAILS ALONG WITH OVERALL AVERAGE SALARY USING WINDOW FUNCTION
+SELECT
+    emp_no,
+    department,
+    salary,
+    AVG(salary) OVER() AS avg_salary
+FROM employees;
+
+-- AGGREGATE MIN AND MAX SALARIES (WITHOUT WINDOW FUNCTION) - RESULTS IN SINGLE ROW PER GROUP (IF GROUPED)
+-- results in EXCEPTION if not grouped
+-- SELECT
+--     emp_no,
+--     department,
+--     salary,
+--     MIN(salary) AS min_salary,
+--     MAX(salary) AS max_salary
+-- FROM employees;
+
+-- AGGREGATE MIN AND MAX SALARIES (WITHOUT WINDOW FUNCTION) - RESULTS IN SINGLE ROW PER GROUP (IF GROUPED)
+SELECT
+    department,
+	AVG(salary) AS avg_salary,
+    MIN(salary) AS min_salary,
+    MAX(salary) AS max_salary
+FROM employees
+GROUP BY department;
+
+-- SHOW EMPLOYEE DETAILS ALONG WITH MIN AND MAX SALARIES ACROSS ALL ROWS
+SELECT
+    emp_no,
+    department,
+    salary,
+    MIN(salary) OVER() AS min_salary,
+    MAX(salary) OVER() AS max_salary
+FROM employees;
+
+-- SHOW EMPLOYEE DETAILS ALONG WITH MIN AND MAX SALARIES PER DEPARTMENT
+SELECT
+    emp_no,
+    department,
+    salary,
+    AVG(salary) OVER(PARTITION BY department) AS dep_avg_salary,
+    MIN(salary) OVER(PARTITION BY department) AS dep_min_salary,
+    MAX(salary) OVER(PARTITION BY department) AS dep_max_salary
+FROM employees;
+
+-- SHOW EMPLOYEE DETAILS ALONG WITH MIN AND MAX SALARIES PER DEPARTMENT
+SELECT
+    emp_no,
+    department,
+    salary,
+    SUM(salary) OVER(PARTITION BY department) AS dept_payroll,
+    SUM(salary) OVER() AS total_payroll
+FROM employees;