Sql server 如何使用DbConnection类从数据库连接和获取数据

如何使用DbConnection类连接到数据库sql server或oracle并从任何表中获取数据。我尝试使用以下代码，但遇到了如下运行时异常：

错误3错误C2664： 'System:：Data:：SqlClient:：SqlDataAdapter:：SqlDataAdapterSystem:：String __gc*，System:：String _gc*'：无法将参数2从“System:：Data:：Common:：DbConnection _gc*”转换为“System:：String _gc*” 在新的SQLDataAdapters上，从[LabOpsStatus]中选择*

---

这段代码出了什么问题？

Shaheer，您需要从提供程序创建连接。不过，我认为我指定为Oracle的提供程序是不正确的

又是一些c代码

DbProviderFactory factory = DbProviderFactories.GetFactory("Oracle");

DbConnection conn = factory.CreateConnection();
conn.ConnectionString = "Data Source=(local);Initial Catalog=myDb;User Id=user;Password=pw;";

DbCommand cmd = factory.CreateCommand();
cmd.Connection = conn;
cmd.CommandText = "Select * from table1";

---

您仍然会遇到的问题是，一旦为SQL创建了连接，就不能将其用于Oracle，除非在同一个Oracle对象中重新创建连接

DbProviderFactory factory = DbProviderFactories.GetFactory("Oracle");

DbConnection conn = factory.CreateConnection();
conn.ConnectionString = "Data Source=(local);Initial Catalog=myDb;User Id=user;Password=pw;";

DbCommand cmd = factory.CreateCommand();
cmd.Connection = conn;
cmd.CommandText = "Select * from table1";

string datosConexion = "Data Source=(local);"
        + "Initial Catalog = myDb ; User Id=user;Password=pw;";

        try
        {
            using (SqlConnection con = new SqlConnection(datosConexion))
            {
                con.Open();
                string textoCmd = "select * from [LabOpsStatus]";

                SqlCommand cmd = new SqlCommand(textoCmd, con);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }