SQL.md

1. Select all records:

   SELECT * FROM Employees;

   Output:

   ID | Name    | Age | Department | Salary
   ----------------------------------------
   1  | Alice   | 30  | HR         | 60000
   2  | Bob     | 25  | IT         | 70000
   3  | Carol   | 27  | IT         | 72000
   4  | Dave    | 35  | Sales      | 80000
   

2. Select specific columns:

   SELECT Name, Salary FROM Employees;

   Output:

   Name  | Salary
   ---------------
   Alice | 60000
   Bob   | 70000
   Carol | 72000
   Dave  | 80000
   

3. Select records with a condition:

   SELECT * FROM Employees WHERE Age > 30;

   Output:

   ID | Name  | Age | Department | Salary
   --------------------------------------
   4  | Dave  | 35  | Sales      | 80000
   

4. Insert a new record:

   INSERT INTO Employees (ID, Name, Age, Department, Salary) VALUES (5, 'Eve', 28, 'HR', 65000);

   Output: (No direct output, but the table will now have an additional record.)

5. Update a record:

   UPDATE Employees SET Salary = 75000 WHERE Name = 'Bob';

   Output: (No direct output, but Bob's salary will be updated to 75000.)

6. Delete a record:

   DELETE FROM Employees WHERE ID = 1;

   Output: (No direct output, but the record with ID 1 will be deleted.)

7. Count the number of records:

   SELECT COUNT(*) FROM Employees;

   Output:

   COUNT(*)
   --------
   4
   

8. Find the average salary:

   SELECT AVG(Salary) FROM Employees;

   Output:

   AVG(Salary)
   ------------
   70500
   

9. Find the maximum salary:

   SELECT MAX(Salary) FROM Employees;

   Output:

   MAX(Salary)
   ------------
   80000
   

10. Find the minimum salary:

    SELECT MIN(Salary) FROM Employees;

    Output:

    MIN(Salary)
    ------------
    60000
    

11. Group records by department and count:

    SELECT Department, COUNT(*) FROM Employees GROUP BY Department;

    Output:

    Department | COUNT(*)
    ----------------------
    HR         | 2
    IT         | 2
    Sales      | 1
    

12. Sort records by salary in descending order:

    SELECT * FROM Employees ORDER BY Salary DESC;

    Output:

    ID | Name  | Age | Department | Salary
    --------------------------------------
    4  | Dave  | 35  | Sales      | 80000
    3  | Carol | 27  | IT         | 72000
    2  | Bob   | 25  | IT         | 75000
    5  | Eve   | 28  | HR         | 65000
    

13. Select records with a salary greater than a certain amount:

    SELECT * FROM Employees WHERE Salary > 65000;

    Output:

    ID | Name  | Age | Department | Salary
    --------------------------------------
    2  | Bob   | 25  | IT         | 75000
    3  | Carol | 27  | IT         | 72000
    4  | Dave  | 35  | Sales      | 80000
    

14. Use DISTINCT to find unique departments:

    SELECT DISTINCT Department FROM Employees;

    Output:

    Department
    ----------------
    HR
    IT
    Sales
    

15. Select records with a specific pattern in a column:

    SELECT * FROM Employees WHERE Name LIKE 'A%';

    Output:

    ID | Name  | Age | Department | Salary
    --------------------------------------
    1  | Alice | 30  | HR         | 60000