c# - 如何使用 SqlCommand 返回多个结果集？

Question

我可以执行多个查询并仅执行一次 SqlCommand 返回它们的结果吗？

Answer 1

参见 SqlDataReader.NextResult (调用 SqlCommand.ExecuteReader 返回一个 SqlDataReader):

Advances the data reader to the next result [set], when reading the results of batch Transact-SQL statements.

例子:

string commandText = @"SELECT Id, ContactId
FROM dbo.Subscriptions;

SELECT Id, [Name]
FROM dbo.Contacts;";


List<Subscription> subscriptions = new List<Subscription>();
List<Contact> contacts = new List<Contact>();

using (SqlConnection dbConnection = new SqlConnection(@"Data Source=server;Database=database;Integrated Security=true;"))
{
    dbConnection.Open();
    using (SqlCommand dbCommand = dbConnection.CreateCommand())
    {
        dbCommand.CommandText = commandText;
        using(SqlDataReader reader = dbCommand.ExecuteReader())
        {
            while(reader.Read())
            {
                subscriptions.Add(new Subscription()
                {
                    Id = (int)reader["Id"],
                    ContactId = (int)reader["ContactId"]
                });
            }

            // this advances to the next resultset 
            reader.NextResult();

            while(reader.Read())
            {
                contacts.Add(new Contact()
                {
                    Id = (int)reader["Id"],
                    Name = (string)reader["Name"]
                });
            }
        }
    }
}

其他例子:

• C# Multiple Result Sets
• Executing a Query That Returns Multiple Result Sets with SqlDataReader : SqlCommand Select « ADO.Net « C# / CSharp Tutorial