C# using SQL, error: Must declare the scalar value @name-CodePudding

Im new to c# and for this I´m supposed to ask for a new name and description for a category and add that to the already existent table, but im having problems with the declaring scalar value as im not sure how to do that.

This i where i ask the values

Console.WriteLine("Category Name? \n");
n= Console.ReadLine();
Console.WriteLine("New description? \n");
d = Console.ReadLine();

And here is where the sql query begins

var sql = new SqlCommand("INSERT INTO Categories (CategoryName, Description) "    
                                 "VALUES (@name, @description", cn)

        SqlParameter name = new SqlParameter();
        name.ParameterName = "@name";
        name.Value = n;

        SqlParameter description = new SqlParameter();
        name.ParameterName = "@description";
        name.Value = d;

        sql.Parameters.Add(name);
        sql.Parameters.Add(description);

The code does ask me to write the name and description in the cmd the error comes after entering the new values. My question is how do i fix the declare scalar value error? Am i not declaring it in here?

    name.ParameterName = "@name";
    name.Value = n;

CodePudding user response：

It looks like you have a simple copy/paste fail, you're replacing the @name parameter with @description

SqlParameter name = new SqlParameter();
name.ParameterName = "@name";
name.Value = n;

SqlParameter description = new SqlParameter();
description.ParameterName = "@description";
description.Value = d;

CodePudding user response：

You have made a simple copy/paste error, as mentioned.

The easiest and most concise way to add properly parameters is to use the constructor of SqlParameter or to use Parameters.Add

const string query = @"
INSERT INTO Categories (CategoryName, Description)
VALUES (@name, @description";
using (var sql = new SqlCommand(query, cn))
{
    sql.Parameters.Add("@name", SqlDbType.VarChar, 100).Value = n;
    sql.Parameters.Add("@description", SqlDbType.VarChar, 100).Value = d;

    sql.ExecuteNonQuery();  // or whatever
}

Note the use of the following best practices:

using block for SqlCommand (the same goes for SqlConnection and SqlDataReader)
A multi-line verbatim string for the actual query batch, which makes it easier to read.
Specify the parameter types and lengths explicitly. This improves performance with regards to implicit conversions and query plan caching.

CodePudding user response：

var sql = new SqlCommand("INSERT INTO Categories (CategoryName, Description) "    
                             "VALUES (@name, @description", cn)

Here your are trying to insert two values and providing 3. This is where you may be getting Error and ofcourse do check out above answers too.