如何用多个表填充数据集？

Posted 2021-04-15

我正在尝试填充包含2个具有一对多关系的表的DataSet。我正在使用DataReader来实现这个目的：

    public DataSet SelectOne(int id)
    {
        DataSet result = new DataSet();
        using (DbCommand command = Connection.CreateCommand())
        {
            command.CommandText = "select * from table1";

            var param = ParametersBuilder.CreateByKey(command, "ID", id, null);
            command.Parameters.Add(param);

            Connection.Open();
            using (DbDataReader reader = command.ExecuteReader())
            {
                result.MainTable.Load(reader);
            }
            Connection.Close();
        }
        return result;
    }

但我只填了一张桌子。我如何实现目标 - 填写两个表格？

如果可能的话，我想使用DataReader而不是DataAdapter。

答案

如果要发出包含多个select语句的单个命令，则可以使用NextResult方法移动到datareader中的下一个结果集：http://msdn.microsoft.com/en-us/library/system.data.idatareader.nextresult.aspx

我展示它如何看起来如下：

public DataSet SelectOne(int id)
{
    DataSet result = new DataSet();
    using (DbCommand command = Connection.CreateCommand())
    {
        command.CommandText = @"
select * from table1
select * from table2
        ";

        var param = ParametersBuilder.CreateByKey(command, "ID", id, null);
        command.Parameters.Add(param);

        Connection.Open();
        using (DbDataReader reader = command.ExecuteReader())
        {
            result.MainTable.Load(reader);
            reader.NextResult();
            result.SecondTable.Load(reader);
            // ...
        }
        Connection.Close();
    }
    return result;
}

另一答案

使用多个表填充DataSet可以通过向数据库发送多个请求或以更快的方式完成：可以在单个请求中将多个SELECT语句发送到数据库服务器。这里的问题是从查询生成的表具有自动名称Table和Table1。但是，生成的表名称可以映射到应该在DataSet中使用的名称。

SqlDataAdapter adapter = new SqlDataAdapter(
      "SELECT * FROM Customers; SELECT * FROM Orders", connection);
adapter.TableMappings.Add("Table", "Customer");
adapter.TableMappings.Add("Table1", "Order");

adapter.Fill(ds);

另一答案

这是一个古老的话题，但对某些人来说可能有用：

        DataSet someDataSet = new DataSet();
        SqlDataAdapter adapt = new SqlDataAdapter();

        using(SqlConnection connection = new SqlConnection(ConnString))
        {
            connection.Open();
            SqlCommand comm1 = new SqlCommand("SELECT * FROM whateverTable", connection);
            SqlCommand comm2g = new SqlCommand("SELECT * FROM whateverTable WHERE condition = @0", connection);
            commProcessing.Parameters.AddWithValue("@0", "value");
            someDataSet.Tables.Add("Table1");
            someDataSet.Tables.Add("Table2");

            adapt.SelectCommand = comm1;
            adapt.Fill(someDataSet.Tables["Table1"]);
            adapt.SelectCommand = comm2;
            adapt.Fill(someDataSet.Tables["Table2"]);
        }

另一答案

Here is very good answer of your question

请参阅以上MSDN页面上提到的示例： -

另一答案

public DataSet GetDataSet()
    {
        try
        {
            DataSet dsReturn = new DataSet();
            using (SqlConnection myConnection = new SqlConnection(Core.con))
            {
                string query = "select * from table1;  select* from table2";
                SqlCommand cmd = new SqlCommand(query, myConnection);
                myConnection.Open();
                SqlDataReader reader = cmd.ExecuteReader();
                dsReturn.Load(reader, LoadOption.PreserveChanges, new string[] { "tableOne", "tableTwo" });
                return dsReturn;
            }
        }
        catch (Exception)
        {
            throw;
        }
    }

另一答案

Load的方法DataTable在NextResult上执行DataReader，因此在使用NextResult时不应该明确地调用Load，否则序列中的奇数表将被省略。

这是使用DataReader加载多个表的通用解决方案。

// your command initialization code here
// ...
DataSet ds = new DataSet();
DataTable t;
using (DbDataReader reader = command.ExecuteReader())
{
  while (!reader.IsClosed)
  {
    t = new DataTable();
    t.Load(rs);
    ds.Tables.Add(t);
  }
}

另一答案

protected void Page_Load(object sender, EventArgs e)
{
    SqlConnection con = new SqlConnection("data source=.;uid=sa;pwd=123;database=shop");
    //SqlCommand cmd = new SqlCommand("select * from tblemployees", con);
    //SqlCommand cmd1 = new SqlCommand("select * from tblproducts", con);
    //SqlDataAdapter da = new SqlDataAdapter();

    //DataSet ds = new DataSet();
    //ds.Tables.Add("emp");
    //ds.Tables.Add("products");
    //da.SelectCommand = cmd;
    //da.Fill(ds.Tables["emp"]);
    //da.SelectCommand = cmd1;

    //da.Fill(ds.Tables["products"]);
    SqlDataAdapter da = new SqlDataAdapter("select * from tblemployees", con);
    DataSet ds = new DataSet();
    da.Fill(ds, "em");
    da = new SqlDataAdapter("select * from tblproducts", con);
    da.Fill(ds, "prod");

    GridView1.DataSource = ds.Tables["em"];
    GridView1.DataBind();
    GridView2.DataSource = ds.Tables["prod"];
    GridView2.DataBind();
}

另一答案

         string connetionString = null;
        SqlConnection connection ;
        SqlCommand command ;
        SqlDataAdapter adapter = new SqlDataAdapter();
        DataSet ds = new DataSet();
        int i = 0;
        string firstSql = null;
        string secondSql = null;

        connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password";
        firstSql = "Your First SQL Statement Here";
        secondSql = "Your Second SQL Statement Here";
        connection = new SqlConnection(connetionString);

        try
        {
            connection.Open();

            command = new SqlCommand(firstSql, connection);
            adapter.SelectCommand = command;
            adapter.Fill(ds, "First Table");

            adapter.SelectCommand.CommandText = secondSql;
            adapter.Fill(ds, "Second Table");

            adapter.Dispose();
            command.Dispose();
            connection.Close();

            //retrieve first table data 
            for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                MessageBox.Show(ds.Tables[0].Rows[i].ItemArray[0] + " -- " + ds.Tables[0].Rows[i].ItemArray[1]);
            }
            //retrieve second table data 
            for (i = 0; i <= ds.Tables[1].Rows.Count - 1; i++)
            {
                MessageBox.Show(ds.Tables[1].Rows[i].ItemArray[0] + " -- " + ds.Tables[1].Rows[i].ItemArray[1]);

            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Can not open connection ! ");
        }