ASP.Net MVC - Insert and Update - sql-server

Question

I'm trying to insert and update into my database but I don't know how to use SQL in this context. Was following iamtimcorey on YouTube: https://www.youtube.com/watch?v=bIiEv__QNxw&t=2322s
Business Logic (EmloyeeProcessor)
public static int CreateEmployee(string Employee_number, string First_name, string Last_name,
string Email, string Research_Area, string Position_held,
string Highest_qualification, string Department_name)
{
Employee_Model data = new Employee_Model
{
Employee_number = Employee_number,
First_name = First_name,
Last_name= Last_name,
Email = Email,
Research_area = Research_Area,
Position_held = Position_held,
Highest_qualification = Highest_qualification,
Department_name = Department_name,
};
string sql = #"DECLARE #var_Department_id int;
SELECT #var_Department_id = Department_id
FROM dbo.Departments
WHERE dbo.Departments.Department_name = #Department_name;
INSERT INTO dbo.Employee (Employee_number, First_name, Last_name, Email, Research_area, Position_held, Highest_qualification, #var_Department_id)
VALUES (#Employee_number, #First_name, #Last_name, #Email, #Research_area, #Position_held, #Highest_qualification, #Department_name);";
return SqlDataAccess.SaveData(sql, data);
}
Department_name = Department_name returns a string that's already present in the Department's Table. Department name is a string in table Departments. I want to pass in the matching Department_id from that table into the New Employee I'm creating.
public static class SqlDataAccess
{
public static string GetConnectionString(string connectionName = "DemoDB")
{
return ConfigurationManager.ConnectionStrings[connectionName].ConnectionString;
}
public static List<T> LoadData<T>(string sql)
{
using (IDbConnection cnn = new SqlConnection(GetConnectionString()))
{
return cnn.Query<T>(sql).ToList();
}
}
}

Answer 1

I think the SQL-query should look like this:
DECLARE #var_Department_id int;
SELECT #var_Department_id = Department_id
FROM dbo.Departments
WHERE dbo.Departments.Department_name = #Department_name;
/*
Final insert into table dbo.Employee.
*/
INSERT INTO dbo.Employee (
Employee_number,
First_name,
Last_name,
Email,
Research_area,
Position_held,
Highest_qualification,
Department_id --This was #var_Department_id in your query
)
VALUES (
#Employee_number,
#First_name,
#Last_name,
#Email,
#Research_area,
#Position_held,
#Highest_qualification,
#var_Department_id --This was #Department_name in your query
);";