添加参数到DbCommand的例外情况

Question

I need an update command with parameters, and for some reasons I can't use stored procedures, actually we generate update command depend on database, table and columns, the following forms are we use:

        string conStr = "Provider=SQLNCLI10;Server=.\\sql2008;DataBase=MyDataBase;Trusted_Connection=true;";

        DbProviderFactory dbFactory = DbProviderFactories.GetFactory("System.Data.OleDb");
        DbConnection dbConnection = dbFactory.CreateConnection();
        dbConnection.ConnectionString = conStr;

        DbCommand dbCommand = dbFactory.CreateCommand();
        dbCommand.CommandText = "UPDATE [Student] SET Name = @Name Where Id = @Id";

        DbParameter param1 = dbCommand.CreateParameter();
        param1.ParameterName = "@Name";
        param1.Value = "LOL";
        DbParameter param2 = dbCommand.CreateParameter();
        param2.ParameterName = "@Id";
        param2.Value = 5;

        dbCommand.Parameters.Add(param1);
        dbCommand.Parameters.Add(param2);

        dbConnection.Open();
        dbCommand.ExecuteNonQuery();
        dbConnection.Close();

But there is an exception:

Must declare the scalar variable "@Name"

Where is the problem in this code? Does anyone have an idea about this?

Answer 1

As you are using System.Data.OleDb as database provider ( regardless you are using a sql server ) you need to use the ? as the parameter placeholder like:

"UPDATE [Student] SET Name = ? Where Id = ?";

By using the System.Data.OleDb provider the names of the parameters doesn`t matter anymore but you need to ensure that the occurance of the parameters match the order the parameterobjects are added to the command objects parameter collection.

EDIT: If you want to keep the @ as parameter placeholder you can just change this:

DbProviderFactory dbFactory = DbProviderFactories.GetFactory("System.Data.OleDb");

to

DbProviderFactory dbFactory = DbProviderFactories.GetFactory("System.Data.SqlClient");

Answer 2

Try that and let me know if it works.

DbParameter param1 = dbCommand.CreateParameter();
param1.ParameterName.AddWithValue("@Name", Textbox1.Text);

or

DbParameter param1 = dbCommand.CreateParameter();
param1.SelectCommand.Parameters.AddWithValue("@Name", Textbox1.Text);

Answer 3

command.CommandText = "EXEC [dbo].[PR_GetPurchase_ProjectBUDetails] " + prjID.ToString()+ " ," + empID.ToString();

Hard code parameters while calling stored procedure .
This solved my issue.