c# - 选择命令参数 C#

Question

我需要获取 SelectCommand.Parameters 的值

你能帮助我吗 ？

string sql = "SELECT area, login, senha FROM tbl_usuarios WHERE login = '" + login + "' AND senha = '" + senha + "'";
adapter = new SqlDataAdapter(sql, conn);
dataTable = new DataTable();

adapter.SelectCommand.Parameters.Add("login", DbType.String);
adapter.SelectCommand.Parameters.Add("senha", DbType.String);

string a = adapter.SelectCommand.Parameters.Add(@"area", DbType.Int16); // Error Coversion
Session.Add("ar", a);

Answer 1

I think the problem is that you are trying to assign the return type from the Add Method (which is a SqlParameter) to a string.

See SqlParameterCollection.Add Method (String, SqlDbType)

I thing what you are looking for is something like

SqlParameter a = adapter.SelectCommand.Parameters.Add(@"area", DbType.Int16);

Answer 2

        bool encontrou = false;
        string sql = "SELECT area, login, senha FROM tbl_usuarios WHERE login = '" + login + "' AND senha = '" + senha + "'";
        command = new SqlCommand(sql, conn);
        try
        {
            conn.Open();
            dataReader = command.ExecuteReader();
            while(dataReader.Read())
            {
                string area = dataReader["area"].ToString();
                Session.Add("area", area);
                encontrou = true;
            }
        }

Answer 3

您的问题不清楚，但是 Add 方法返回一种 SqlParameter 类型，因此：

string a = adapter.SelectCommand.Parameters.Add(@"area", DbType.Int16);

错了..它需要：

SqlParameter a = adapter.SelectCommand.Parameters.Add(@"area", DbType.Int16);

Answer 4

检查 MSDN 上的代码：SqlDataAdapter.SelectCommand 属性

也许你需要的是：

获取数据表上的值：

string sql = "SELECT area, login, senha FROM tbl_usuarios WHERE login = '" + login + "' AND senha = '" + senha + "'";
adapter = new SqlDataAdapter(sql, conn);
dataTable = new DataTable();
adapter.Fill(dataTable);

string a  = dataTable.Rows["area"].toString(); //get area value..
Session.Add("ar", a);

问候