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Insert value into SQL Database from business layer

Posted on 2010-11-20
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Last Modified: 2012-05-10
I'm creating a C# application using a three tiered approach. I've passed my string variable(Rating) from the presentation layer to the business layer now I need to pass it to the data access layer and insert it into my sql database. I have no idea how where to begin.
//Busness layer 
public BLL()
        {
        }

        //Properties
        public string Rating
        {
            get
            {
                return rating;
            }
            set
            {
                rating = value;
            }
          }
        }

//Data access layer
        public int Save(string sql) 
        {
            string sqlIns = "INSERT INTO table (Rating) VALUES (@Rating)";
            conn.Open();
            OleDbCommand cmd = new OleDbCommand(sql, conn);
            return cmd.ExecuteNonQuery();

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Question by:98fatboyrider
  • 2
3 Comments
 
LVL 52

Accepted Solution

by:
Carl Tawn earned 250 total points
ID: 34181068
Normally you would pass a business object between the layers, or have a method in your DAL that accepts parameters from a business object (depending on what pattern you are using).

It's not clear from the code you have posted how the Rating property fits into your overall structure. However, in very simply terms, if you are saving just the rating by itself then you would change the method in your DLL to something like:
public void Save(string rating)
{
     string sqlIns = "INSERT INTO table (Rating) VALUES (@Rating)";
     
     SqlCommand cmd = new SqlCommand(sqlIns, conn);
     cmd.Parameters.AddWithValue("@Rating", rating);

     try
    {
        conn.Open();
        cmd.ExecuteNonQuery();
    }
    catch
   {
        // do something with the exception
   }
    finally
    {
           if (conn.ConnectionState != ConnectionState.Closed)
               conn.Close();
    }
}

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You might the have a Save() method in your BLL to save the data:
    // in BLL
    public void Save()
    {
           DAL dal = new DAL();
           dal.Save(this.Rating);
    }

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Just a simple example based on what I could glean from your current code. But hopefully it will provide you with a starting point.
0
 

Author Comment

by:98fatboyrider
ID: 34184178
I believe I'm close but not quite there yet. All I need to do is pass a textbox value to the business layer then insert it into my database from the data access layer. Can you see where I’m going wrong?.
//Presentation layer
private void btnAddRating_Click(object sender, EventArgs e)
        {
            string Rating = txtNewRating.Text.ToUpper();
            BLL setRating = new BLL();
            Rating = setRating.ToString();
            setRating.Save();
        }
//Busness layer
public class BLL
    {
        private string _rating;
        //Default constructor
        public BLL()
        {
        }
        //Properties
        public string Rating
        {
            get
            {
                return _rating;
            }
            set
            {
                _rating = value;
            }
        }
public void Save()
        {
            DAL dal = new DAL();
            dal.Save(this.Rating);
        }
  }
//Data access layer

       //Getting all ratings from ratings table
        public DataSet getRatings(string sql)
        {
            // Connection and SQL strings
            string SQL = "SELECT * FROM tblRating";
            try
            {
                // create a connection object
                string ConnectionString = "Data Source=.\\SQLExpress;Integrated Security=true; AttachDbFilename=D:\\MoviesDB\\MovieDB.mdf;User Instance=true;";
                SqlConnection conn = new SqlConnection(ConnectionString);
                // create command object
                SqlCommand cmd = new SqlCommand(SQL, conn);
                DataSet ds = new DataSet();
                // open connection
                conn.Open();
                // call command's ExcuteReader
                SqlDataAdapter da = new SqlDataAdapter(SQL, conn);
                da.Fill(ds);
                return ds;
           }
            finally
            {
                conn.Close();
            }
        }

 public void Save(string rating)
{
     string sqlIns = "INSERT INTO table (Rating) VALUES (@Rating)";
     
     SqlCommand cmd = new SqlCommand(sqlIns, conn);
     cmd.Parameters.AddWithValue("@Rating", rating);

     try
     {
         conn.Open();
         cmd.ExecuteNonQuery();
     }
     catch
     {
         // do something with the exception
     }
     finally
     {
         if (conn.ConnectionState != ConnectionState.Closed)
             conn.Close();
     }
    }
   }

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0
 
LVL 52

Assisted Solution

by:Carl Tawn
Carl Tawn earned 250 total points
ID: 34184214
This block is incorrect:
            BLL setRating = new BLL();
            Rating = setRating.ToString();
            setRating.Save()

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It should be something more like:
            BLL setRating = new BLL();
            setRating.Rating = Rating;
            setRating.Save()

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