requests.sql

--Task 1
SELECT FirstName +' ' + LastName AS [Full Name], Salary
FROM Employees
WHERE Employees.Salary = (
SELECT MIN(Salary)
FROM Employees)

--Task 2
SELECT FirstName +' ' + LastName AS [Full Name], Salary
FROM Employees
WHERE Employees.Salary < (
SELECT MIN(Salary + (Salary * 0.1))
FROM Employees)

--Task 3
SELECT FirstName +' ' + LastName AS [Full Name], d.Name, Salary
FROM Employees e
    JOIN Departments d
    ON e.DepartmentID = d.DepartmentID
WHERE Salary = (
SELECT MIN(Salary)
FROM Employees
WHERE DepartmentId = e.DepartmentID
)

--Task 4
SELECT AVG(Salary) AS [Average Salary]
FROM Employees
WHERE DepartmentID = 1

--Task 5
SELECT AVG(Salary) AS [Average Salary], d.Name AS [Department Name]
FROM Employees e
    JOIN Departments d
    ON e.DepartmentID = d.DepartmentID
WHERE d.Name = 'Sales'
GROUP BY d.Name

--Task 6
SELECT count(*) AS [Employees in Sales]
FROM Employees e
    JOIN Departments d
    ON e.DepartmentID = d.DepartmentID
WHERE d.Name = 'Sales'

--Task 7
SELECT COUNT(*) AS [Employees with manager]
FROM Employees
WHERE ManagerID IS NOT NULL

--Task 8
SELECT COUNT(*) AS [Managers]
FROM Employees
WHERE ManagerID IS NULL

--Task 9
SELECT d.Name AS [Department Name], AVG(Salary) AS [AVG Salary]
FROM Employees e
    JOIN Departments d
    ON d.DepartmentID = e.DepartmentID
GROUP BY d.Name

--Task 10
SELECT COUNT(*) AS [Employees Count], t.Name AS [Town], d.Name AS [Department Name]
FROM Employees e
    JOIN Departments d
    ON d.DepartmentID = e.DepartmentID
    JOIN Addresses ad
    ON e.AddressID = ad.AddressID
    JOIN Towns t
    ON ad.TownID = t.TownID
GROUP BY d.Name, t.Name

--Task 11 //Need fixing I guess??
SELECT m.FirstName + ' ' + m.LastName AS [Full Name], COUNT(*) AS [Number of Employees]
FROM Employees e
    JOIN Employees m
    ON e.ManagerID = m.ManagerID
GROUP BY m.FirstName, m.LastName
HAVING COUNT(*) = 5

--Task 12
SELECT e.FirstName + ' ' + e.LastName AS [Employee Full Name],
    COALESCE(m.FirstName + ' ' + m.LastName, 'no manager') AS [Manager Name]
FROM Employees e
    LEFT OUTER JOIN Employees m
    ON e.ManagerID = m.EmployeeID

--Task 13
SELECT e.FirstName + ' ' + e.LastName AS [Employee Full Name]
FROM Employees e
WHERE LEN(e.LastName) = 5

--Task 14
SELECT FORMAT(GETDATE(),'d.MM.yyyy hh:mm:ss:ff') AS [Current Date and Time]

--Task 15
CREATE TABLE Users
(
    Id INT IDENTITY PRIMARY KEY,
    UserName NVARCHAR(20) UNIQUE NOT NULL,
    UserPassword NVARCHAR(100) NOT NULL CHECK( LEN(UserPassword) >= 5),
    FullName NVARCHAR(50),
    LastLoginTime DATETIME
)

--Task 16
INSERT INTO Users
    (UserName, UserPassword, FullName, LastLoginTime)
VALUES
    ('User1', 'password1', 'user1 fullname', NULL)

INSERT INTO Users
    (UserName, UserPassword, FullName, LastLoginTime)
VALUES
    ('User2', 'password2', 'user2 fullname', GETDATE())

SELECT *
FROM Users
WHERE FORMAT(Users.LastLoginTime, 'd.MM.yyyy') = FORMAT(GETDATE(), 'd.MM.yyyy')

--Task 17
CREATE TABLE Groups
(
    Id INT IDENTITY PRIMARY KEY,
    Name NVARCHAR(20) UNIQUE
)

--Task 18
ALTER TABLE Users
ADD GroupId INT FOREIGN KEY REFERENCES Groups(GroupId)

INSERT INTO Groups
    (Name)
VALUES
    ('Guests')
INSERT INTO Groups
    (Name)
VALUES
    ('Moderators')
INSERT INTO Groups
    (Name)
VALUES
    ('SysAdmins')
INSERT INTO Groups
    (Name)
VALUES
    ('Users')

UPDATE Users
SET GroupId = 5
WHERE Id = 2
UPDATE Users
SET GroupId = 1
WHERE Id = 1

--Task 19
INSERT INTO Users
    (UserName, UserPassword, FullName, LastLoginTime, GroupId)
VALUES
    ('user13', 'parola1234', 'gosho peshev', GETDATE(), 6),
    ('user42', 'parola234', 'pesho goshov', GETDATE(), 5),
    ('user99', 'parola34', 'stamat peshev', GETDATE(), 7)

INSERT INTO Groups
    (Name)
VALUES
    ('Super Users'),
    ('Editors'),
    ('DB Admins')

--Task 20
UPDATE Users
SET UserName = 'Edited User'
WHERE Id = 5

UPDATE Groups
SET Name = 'Edited Group'
WHERE GroupId = 5

--Task 21
DELETE FROM Users
WHERE Id = 4

DELETE FROM Groups
WHERE GroupId = 8