Question

I call this method on form load ivent GetProducts(” “);
This Query works fine in sql. It was working till i added WHERE
When i use debugger on this line >> SqlDataReader myReader = cmd.ExecuteReader();
Can anyone advice me something?

 public void GetProducts(string find)
    {
        try
        {
            using (SqlCommand cmd = new SqlCommand("SELECT ID, BarCode, ArtNumber, ProductName, Price, SelfPrice, PriceWithOutAWD, TotalSelfPrice, UnitsInStock, " +
                                                " Comment, InputDateTime, InputQuantity, Margin, CategoryName, TypeName, ExpDate FROM GetProducts"+
                                                "WHERE BarCode LIKE '%@F%' OR ArtNumber LIKE '%@F%' OR ProductName LIKE '%@F%' OR Price LIKE '%@F%' OR Comment LIKE '%@F%' ", 
                                                new SqlConnection(Program.ConnectionString)))
            {
                cmd.Parameters.AddWithValue("@F", find);
                cmd.Connection.Open();

                SqlDataReader myReader = cmd.ExecuteReader();
                while (myReader.Read())
                {

                    ProductTable.Rows.Add
                        (
                        (int)myReader["ID"],
                        myReader["BarCode"].ToString(),
                        myReader["ArtNumber"].ToString(),
                        myReader["ProductName"].ToString(),
                        (decimal)myReader["Price"],
                        (decimal)myReader["SelfPrice"],
                        (decimal)myReader["PriceWithOutAWD"],
                        myReader["TotalSelfPrice"].ToString(),
                        myReader["UnitsInStock"].ToString(),
                        myReader["Comment"].ToString(),
                        myReader["InputDateTime"].ToString(),
                        myReader["InputQuantity"].ToString(),
                        myReader["Margin"].ToString(),
                        myReader["CategoryName"].ToString(),
                        myReader["TypeName"].ToString(),
                        myReader["ExpDate"].ToString()
                        );
                }
                cmd.Connection.Close();
            }
        }
        catch (Exception)
        {
            MessageBox.Show(Program.MsgError1, "Acid", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }

    }

Answer 1

... FROM GetProducts"+
"WHERE BarCode LIKE ...

Should be (note additional space between GetProducts and WHERE)

... FROM GetProducts "+
"WHERE BarCode LIKE ...

Also don’t use

WHERE BarCode LIKE '%@F%'

Either Use

WHERE BarCode LIKE '%' + @F + '%' 

Or alternatively have the parameter value contain the wild cards and use

cmd.Parameters.AddWithValue("@F", "%" + find + "%"); 
 ...
WHERE BarCode LIKE @F

If you will always be searching with a leading wildcard however you should probably use

WHERE CHARINDEX(@F,BarCode) > 0

Your query won’t be able to use an index anyway and this method avoids issues if the users search for substrings that contain characters that have a special meaning in the pattern syntax.

However from the amount of columns you are searching and the leading wildcards you should probably use full text indexing for this anyway.