Question

RhinoETL上的许多示例代码都谈到从csv文件加载并插入数据库。如何执行从SQL Server数据库的读取并将其行输出到控制台？您是否有示例代码来执行简单的dbread和批处理读取？

author's blog显示了一些示例代码，但是它似乎不完整，或者我遗漏了一些东西。

我的无效代码

public class ReadBuildInfos : ConventionInputCommandOperation
{
    public ReadBuildInfos(ConnectionStringSettings csSettings) : base(csSettings)
    {
        Command = "SELECT Key, Value FROM dbo.BuildInfos WITH (NOLOCK);";
    }

    public override IEnumerable<Row> Execute(IEnumerable<Row> rows)
    {
        foreach (Row row in rows)
        {
            yield return row;
        }
    }
}

Answer 1

直接用Rhino.Etl调试后，发现我犯了2个错误：

ConnectionStringSettings应该包含providerName。 RhinoETL对此提出了例外，但我不知何故

    var csString = new ConnectionStringSettings("myConnection2",
        "Server=yourdatabasehere.database.windows.net;Database=MyDbName;User ID=youruser;Password=yourpassword",
        "System.Data.SqlClient"); //I was missing this.
    Register(new ReadBuildInfosConvention(csString));

作者的博客已完成。 Execute方法不应被覆盖。 SQL Reader如下所示：

public class ReadBuildInfosConvention : ConventionInputCommandOperation
{
    public ReadBuildInfosConvention(ConnectionStringSettings csSettings) : base(csSettings)
    {
        Command = "SELECT [Key], [Value] FROM BuildInfos WITH (NOLOCK);";
    }
}

因为基本的Execute方法已经可以正确处理数据库读取

    public override IEnumerable<Row> Execute(IEnumerable<Row> rows)
    {
        using (IDbConnection connection = Use.Connection(ConnectionStringSettings))
        using (IDbTransaction transaction = BeginTransaction(connection))
        {
            using (currentCommand = connection.CreateCommand())
            {
                currentCommand.Transaction = transaction;
                PrepareCommand(currentCommand);
                using (IDataReader reader = currentCommand.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        yield return CreateRowFromReader(reader);
                    }
                }
            }

            if (transaction != null) transaction.Commit();
        }
    }

这里是工作中的VS solution with logging。

如何使用RhinoETL框架从SQL Server表中读取数据？

1 个答案: