Search Function

One thing that's still wrong is that you're calling ToString() in these lines:

cmd.Parameters.Add(new SqlParameter(@"minPrice", SqlDbType.Decimal)).Value = minPrice.ToString();
cmd.Parameters.Add(new SqlParameter(@"maxPrice", SqlDbType.Decimal)).Value = maxPrice.ToString();

even though the type of the parameters is decimal.

I assume that the types you're using for the parameters are compatible with the actual types in the database table.

I'd also make sure that p.Color and p.Type are empty strings rather than null.

Look at your query and ensure that the parameters in the query match the parameters you specify.

Then look at sample uses of the SqlParameter class; the "@" is used for two entirely different purposes. You are using it the C# way but you want to use it the SQL parameter way.

What am I doing wrong here ?

public void SearchProduct(Product p, DataGridView dgv, int minSize, int maxSize, decimal minPrice, decimal maxPrice)
        {
            sqlConn.Open();
            string query = "SELECT * FROM tbl_Products WHERE (Size >= @minSize AND Size <= @maxSize) AND ([Buying Price] >= @minPrice AND [Buying Price] <= @maxPrice)";

            cmd = new SqlCommand(query, sqlConn);
            cmd.Parameters.Add(new SqlParameter(@"Color", SqlDbType.VarChar)).Value = p.Color;
            cmd.Parameters.Add(new SqlParameter(@"minSize", SqlDbType.Int)).Value = minSize;
            cmd.Parameters.Add(new SqlParameter(@"maxSize", SqlDbType.Int)).Value = maxSize;
            cmd.Parameters.Add(new SqlParameter(@"minPrice", SqlDbType.Decimal)).Value = minPrice.ToString();
            cmd.Parameters.Add(new SqlParameter(@"maxPrice", SqlDbType.Decimal)).Value = maxPrice.ToString();
            cmd.Parameters.Add(new SqlParameter(@"Type", SqlDbType.VarChar)).Value = p.Type;

           
            if (p.Color != "" && p.Type != "")
            {
                query += "AND (Colour = @Color) AND (Type = @Type)";
            }
           
            else if (p.Color != "")
            {
                query += "AND (Colour = @Color)";
            }

            else if (p.Type != "")
            {
                query += "AND (Type = @Type)";
            }

            ds = new DataSet("products");
            da = new SqlDataAdapter(cmd);

            SqlCommandBuilder sqb = new SqlCommandBuilder(da);

            da.Fill(ds, "tbl_Products");

            dgv.DataSource = ds.Tables["tbl_Products"];
            sqlConn.Close();
        }

But What about this : string queryString = "SELECT * FROM table WHERE (size >= @minSize AND size <= @maxSize) AND (price >= @minPrice AND price <= @maxPrice) ";


This wont work in this case right ? Can you please give me ax example if its possible can should it be dont so that the user can search for data with 2 entries 3 or even 1 (2 entries ex: only colour and type) (1 entry ex: only sizes max and min) etcc.... Thanks

Yes of course....the user can type and choose any different posibilities say if the user only chooses a colour all the clothes in that colour should show up with all sizes and all prices and type. You can find a screenshot below with my new GUI cause I removed the radio buttons with textboxes.



ScreenShot -----> http://imageshack.us/photo/my-images/88/searchid.jpg/

Regarding to this post :
 string queryString = "SELECT * FROM table WHERE (size >= @minSize AND size <= @maxSize) AND (price >= @minPrice AND price <= @maxPrice) ";

if (colour != "" && type != "") { queryString += "AND (colour = @colour) AND (type = @type)"; }

else if (color != "") { queryString += "AND (colour = @colour)"; }

else if (type != "") { queryString += "AND (type = @type)"; }


What if you dont have and price range nor size range just a color or just a type. It won't work right ?

For those last two parameters, you don't want to convert them to strings. So, they should be:

cmd.Parameters.Add(new SqlParameter(@"minPrice", SqlDbType.Float)).Value = minPrice;
cmd.Parameters.Add(new SqlParameter(@"maxPrice", SqlDbType.Float)).Value = maxPrice;

Also you'll need to redeclare the minPrice and maxPrice variables as double (assuming the database field contains 8 byte floats) rather than decimal.

cmd.Parameters.Add(new SqlParameter(@"minSize", SqlDbType.Int)).Value = minSize;
 cmd.Parameters.Add(new SqlParameter(@"maxSize", SqlDbType.Int)).Value = maxSize;
 cmd.Parameters.Add(new SqlParameter(@"minPrice", SqlDbType.Float)).Value = minPrice.ToString();
 cmd.Parameters.Add(new SqlParameter(@"maxPrice", SqlDbType.Float)).Value = maxPrice.ToString();


 What am i doing wrong about the conversion ?

To do it the way I was suggesting, you would usually have a simple query such as "SELECT * FROM YOURTABLE". Then the filter would be specified dynamically. Unfortunately it does not support parameters, so you would have to put the data in the filter instead of using "@SizeRange" or parameters such as that.

I don't know if I can do this or not

SELECT * FROM YOURTABLE WHERE SizeRange = @SizeRange OR Colors = @Colors OR PriceRanage = @PriceRange OR Type = @Type

 Cause I need the search to work even if the user doesn't tick everything that is if the user only choose a type and press search it works on the type. If the user enter a type and a colour it filters both. What do you think ? Best Regards

There is a lot that you are not telling us. So we must guess. Please excuse us if we guess wrong.

I will assume that the big grey area at the lower half of the form is a DataGridView, but you did not tell us what it is. I will also assume that the DataGridView is bound to the data, but realistically speaking if it was then you would have said so. When I say "DataGridView is bound to the data" I mean something such as in my Database Table Update in a DataGridView without Writing Code. If you bind the control to the data, then you can filter using the data source (actually the BindingSource for the control). The filter would be the same as the When part of a SQL query. Or at least, as far as I know the filter is the same as a SQL  query Where clause.

So is that the type of thing you need?