Stackoverflow - Fill SQL database from a CSV File, Sql Server

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CREATE TABLE Employee 
(
    EmployeeNumber int PRIMARY KEY,    
    EmployeeName varchar(10),
    LoginName varchar(10)
)

CREATE TABLE [Group]
(
    GroupId int identity(1,1) PRIMARY KEY,
    GroupName varchar(20) 
)

CREATE TABLE EmployeeGroup
(
    EmployeeNumber int,
    GroupId int
)

CREATE TABLE Stage
(
    EmployeeNumber int,
    EmployeeName varchar(10),
    LoginName varchar(10),
    GroupName varchar(20)
)

INSERT INTO Stage VALUES
(23567, 'John Doe', 'JDoe', 'Finance'),
(57831, 'Bob Lynn', 'Blynn', 'Administrators'),
(23567, 'John Doe', 'JDoe', 'Human Resources')

INSERT INTO Employee (EmployeeNumber, EmployeeName, LoginName)
    SELECT DISTINCT EmployeeNumber, EmployeeName, LoginName
    FROM Stage

INSERT INTO [Group] (GroupName)
    SELECT DISTINCT GroupName 
    FROM Stage

INSERT INTO EmployeeGroup(EmployeeNumber, GroupId)
    SELECT DISTINCT EmployeeNumber, GroupId
    FROM Stage s
    INNER JOIN [Group] g ON s.GroupName = g.GroupName

SELECT *
FROM Stage

SELECT *
FROM Employee

SELECT *
FROM [Group]

SELECT *
FROM EmployeeGroup

View schema
Execution time: 0,03 sec, rows selected: 11, rows affected: 11, absolute service time: 0,19 sec