Displaying different values from same table and column after comparing - sql

Question

public partial class UserProfile : System.Web.UI.Page
{
private static int _userId = 0 ;
protected void Page_Load(object sender, EventArgs e)
{
string FoB;
if (Session["user"] != null)
{
_userId = DataManager.GetUserId(Session["user"].ToString());
}
string connection = WebConfigurationManager.ConnectionStrings["Database"].ConnectionString;
SqlConnection conn = new SqlConnection(connection);
SqlCommand comm = new SqlCommand("SELECT * from dbo.Rating where UserID=_userId", conn);
SqlDataReader reader;
conn.Open();
reader = comm.ExecuteReader();
reader.Read();
FoB = reader["GenreID"].ToString();
if(FoB=="1" )
{
FB.Text = reader["RatingValue"].ToString();
};
}
while (reader.HasRows);
reader.Close();
conn.Close();
}
}
I have a table named rating. It has 4 columns
RatingId, UserID, GenreID,Rating value
I want to display rating value on a label based on the current user logged in and different rating value against different Genres. UserID and GenreID are foreign keys from table Genre and User.
Edit (comment)
CREATE TABLE [dbo].[Rating] (
[RatingID] INT IDENTITY (1, 1) NOT NULL,
[UserID] INT NULL, [GenreID] INT NOT NULL,
[RatingValue] INT NOT NULL,
PRIMARY KEY CLUSTERED ([RatingID] ASC),
CONSTRAINT [FK_Rating_Genre] FOREIGN KEY ([GenreID])
REFERENCES [dbo].[Genre] ([GenreID])
ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT [FK_Rating_User] FOREIGN KEY ([UserID])
REFERENCES [dbo].[User] ([UserID])
ON DELETE CASCADE ON UPDATE CASCADE );
I want to show 8 different rating values of 8 different genres by 1 single current user.

Answer 1

If I understand you correctly, you want to map your label to different columns, based on another, discriminating column:
using (var conn = new SqlConnection(connection))
using (var comm = new SqlCommand("SELECT * from dbo.Rating where UserID=#userId", conn))
{
comm.Parameters.AddWithValue("#userId", _userId);
conn.Open();
using (var reader = comm.ExecuteReader())
{
if (reader.HasRows && reader.Read())
{
FB.Text = reader["GenreID"].ToString() == "1"
? reader["RatingValue"].ToString();
: reader["SomeOtherColumn"].ToString();
}
}
}
If one or more of the columns to be mapped reside in another table other than Rating, you'll need to join to that table - we'll need to see your table structures to help you.
Edit, re displaying 8 Genres
I've assumed the User and Genre tables both have a column Name - join to these tables to look up the rating. The GROUP and MAX will eliminate any cases where the same user has more than one rating in the same Genre (switch the MAX to AVG or MIN if you need otherwise). Top 8 will restrict the genres. So adjust the Sql like so:
SELECT TOP 8 u.Name AS UserName, g.Name as GenreName, MAX(r.RatingValue) AS TopRating
FROM dbo.Rating r
INNER JOIN dbo.[User] u
ON r.UserId = u.UserID
INNER JOIN dbo.[Genre] g
ON r.GenreID = g.GenreID
WHERE UserID=#userId
GROUP BY u.Name, g.Name
ORDER BY g.Name;
Now, for user interface, you won't be able to display a table in a single label. The easiest would simply be to bind the result of the reader directly to a new GridView control on your WebForm
using (var reader = comm.ExecuteReader())
{
if (reader.HasRows)
{
gridView.DataSource = reader;
gridView.DataBind();
}
}
This will show a table with 3 columns matching the selected columns, and and up to 8 rows.