未定义GridView行更新SQL Server参数

Question

下面是单击更新按钮后更新行的方法。我的SQL Server存储过程在更新之前期望现有公司名称，新公司名称以及是否存在。大胆的部分是它破碎的地方。当我选择编辑时，我想在更新之前解析公司名称行中的当前值。

protected void CompanyTable_RowUpdating(object sender, System.Web.UI.WebControls.GridViewUpdateEventArgs e)
{
    string connectionString = ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;

    SqlConnection cn = new SqlConnection(connectionString);

    using (SqlCommand cmd = new SqlCommand("[updateCompanyName]", cn))
    {
        cmd.CommandType = CommandType.StoredProcedure;

        GridViewRow row = CompanyTable.SelectedRow;
        cmd.Parameters.AddWithValue("@CurrentCompanyName", CompanyTable.Rows[e.RowIndex].Cells[0].Controls[0]);
        cmd.Parameters.AddWithValue("@NewCompanyName", CompanyInputTextBox.Text).Direction = ParameterDirection.Input;
        SqlParameter objisExists = new SqlParameter("@isExists", SqlDbType.Int);
        objisExists.Direction = ParameterDirection.Output;
        cmd.Parameters.Add(objisExists);

        cn.Open();
        cmd.ExecuteNonQuery();
        cn.Close();

        int isExists = Convert.ToInt32(cmd.Parameters["@isExists"].Value.ToString());

        if (isExists == 0)
        {
            Page.ClientScript.RegisterStartupScript(this.GetType(), "111", "AddCompanySuccess();", true);
        }
        else if (isExists == 1)
        {
            Page.ClientScript.RegisterStartupScript(this.GetType(), "111", "CompanyExistsValidation();", true);
        }
    }
}

存储过程参数：

ALTER PROCEDURE [dbo].[updateCompanyName] 
    @CurrentCompanyName VARCHAR(50),
    @NewCompanyName VARCHAR(50),
    @IsExists INT = 0 OUT

我在SQL中的更新：

DECLARE @CompanyID INT

SELECT @CompanyID = CompanyID 
FROM company 
WHERE companyname = @CurrentCompanyName

BEGIN
    IF EXISTS (SELECT CompanyName FROM company 
               WHERE companyname = @NewCompanyName )
    BEGIN
         SET @IsExists = 1
    END
    ELSE
    BEGIN   
        UPDATE COMPANY
        SET CompanyName = @NewCompanyName 
        WHERE companyid = @CompanyID

        SET @IsExists = 0
    END
END

PRINT @isexists