web-dev-qa-db-ja.com

SqlCommandで複数の結果セットを返すにはどうすればよいですか？

複数のクエリを実行し、SqlCommandを一度だけ実行して結果を返すことはできますか？

c#sql-serverado.net
44
Doug

SqlDataReader.NextResult （ SqlCommand.ExecuteReader の呼び出しからSqlDataReaderが返される）を参照してください。

バッチTransact-SQLステートメントの結果を読み取るときに、データリーダーを次の結果[セット]に進めます。

例：

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"]
                });
            }
        }
    }
}

他の例：

58
user166390

Stored Procedureには複数の選択があり、DataSetを埋めます。

using (SqlConnection conn = new SqlConnection(connection))
{
    DataSet dataset = new DataSet();
    SqlDataAdapter adapter = new SqlDataAdapter();
    adapter.SelectCommand = new SqlCommand("MyProcedure", conn);
    adapter.SelectCommand.CommandType = CommandType.StoredProcedure;
    adapter.Fill(dataset);
    return dataset;
}

返されるデータセットには、ストアドプロシージャの各選択のTables配列にDataTableが含まれます。

44
Dave Zych

「dapper」などのツールは、アドホックテキストクエリを使用するかストアドプロシージャを使用するかに関係なく、これを非常に簡単にします。例えば：

using(var multi = conn.QueryMultiple(sql, args))
{
    var customers = multi.Read<Customer>().AsList(); // first grid
    var regionName = multi.ReadFirstOrDefault<string>(); // second grid
    var addresses = multi.Read<Address>().AsList(); // third grid
    // todo: use those things
}

個々のグリッドは、IEnumerable<T>へのオプションのパラメーターを介してなしバッファリング（リーダー自体の上のRead[<T>]として）読み取ることもできます。

2
Marc Gravell

これは、複数の結果セットを返すために使用しているものです。

public abstract class BaseRepo
{
    private string _connectionString;

    protected BaseRepo(string connectionString)
    {
        _connectionString = connectionString;
    }

    private SqlConnection GetSqlConnection(int commandTimeout, CommandType commandType, ref SqlCommand sqlCmd)
    {
        var connection = new SqlConnection(_connectionString);
        connection.Open();
        sqlCmd.Connection = connection;
        sqlCmd.CommandTimeout = commandTimeout;
        sqlCmd.CommandType = commandType;
        return connection;
    }

    protected int ExecuteSql(SqlCommand sqlCmd, int commandTimeout = 30, CommandType commandType = CommandType.Text)
    {
        using (var connection = GetSqlConnection(commandTimeout, commandType, ref sqlCmd))
        {
            return sqlCmd.ExecuteNonQuery();
        }
    }

    protected IEnumerable<T> ExecuteSqlReader<T>(Func<IDataRecord, T> CreateObject, SqlCommand sqlCmd, int commandTimeout = 30, CommandType commandType = CommandType.Text)
    {
        using (var connection = GetSqlConnection(commandTimeout, commandType, ref sqlCmd))
        {
            using (var reader = sqlCmd.ExecuteReader())
                return ExecuteReader(CreateObject, reader);
        }
    }

    protected Tuple<IEnumerable<T1>, IEnumerable<T2>> ExecuteSqlReader<T1,T2>(Func<IDataRecord, T1> CreateObject1, Func<IDataRecord, T2> CreateObject2,  SqlCommand sqlCmd, int commandTimeout = 30, CommandType commandType = CommandType.Text)
    {
        using (var connection = GetSqlConnection(commandTimeout, commandType, ref sqlCmd))
        {
            using (var reader = sqlCmd.ExecuteReader())
            {
                var result1 = ExecuteReader(CreateObject1, reader).ToList();
                var result2 = ExecuteReader(CreateObject2, reader).ToList();
                return Tuple.Create<IEnumerable<T1>, IEnumerable<T2>>(result1, result2);
            }
        }
    }

    protected Tuple<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>> ExecuteSqlReader<T1, T2, T3>(Func<IDataRecord, T1> CreateObject1, Func<IDataRecord, T2> CreateObject2, Func<IDataRecord, T3> CreateObject3, SqlCommand sqlCmd, int commandTimeout = 30, CommandType commandType = CommandType.Text)
    {
        using (var connection = GetSqlConnection(commandTimeout, commandType, ref sqlCmd))
        {
            using (var reader = sqlCmd.ExecuteReader())
            {
                var result1 = ExecuteReader(CreateObject1, reader).ToList();
                var result2 = ExecuteReader(CreateObject2, reader).ToList();
                var result3 = ExecuteReader(CreateObject3, reader).ToList();
                return Tuple.Create<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>>(result1, result2, result3);
            }
        }
    }

    protected Tuple<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>> ExecuteSqlReader<T1, T2, T3, T4>(Func<IDataRecord, T1> CreateObject1, Func<IDataRecord, T2> CreateObject2, Func<IDataRecord, T3> CreateObject3, Func<IDataRecord, T4> CreateObject4, SqlCommand sqlCmd, int commandTimeout = 30, CommandType commandType = CommandType.Text)
    {
        using (var connection = GetSqlConnection(commandTimeout, commandType, ref sqlCmd))
        {
            using (var reader = sqlCmd.ExecuteReader())
            {
                var result1 = ExecuteReader(CreateObject1, reader).ToList();
                var result2 = ExecuteReader(CreateObject2, reader).ToList();
                var result3 = ExecuteReader(CreateObject3, reader).ToList();
                var result4 = ExecuteReader(CreateObject4, reader).ToList();
                return Tuple.Create<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>>(result1, result2, result3, result4);
            }
        }
    }

    private IEnumerable<T> ExecuteReader<T>(Func<IDataRecord, T> CreateObject, SqlDataReader reader)
    {
        while (reader.Read())
        {
            yield return CreateObject(reader);
        }
        reader.NextResult();
    }
}

それから私はそれを次のように継承します：

public class ReviewRepo : BaseRepo
{
    public ReviewRepo(string connectionString) : base(connectionString) { }

    public ReviewPageableResult GetAllReviews(string productType, string serviceType, int pageNumber, int itemsPerPage, string sortBy, string sortDirection)
    {
        var parameters = new List<SqlParameter>
        {
            new SqlParameter("ProductRefDescription", productType),
            new SqlParameter("ServiceRefDescription", serviceType),
            new SqlParameter("ZipCodes", "NULL"),
            new SqlParameter("PageNumber", pageNumber),
            new SqlParameter("ItemsPerPage", itemsPerPage),
            new SqlParameter("SortBy", sortBy),
            new SqlParameter("SortDirection", sortDirection)
        };
        var cmd = new SqlCommand("dbo.GetReviews");
        cmd.Parameters.AddRange(parameters.ToArray());
        var results = ExecuteSqlReader(CreateReview, CreateReviewPageableResult, cmd, commandType: CommandType.StoredProcedure);
        var reviewResult = results.Item2.Single();
        reviewResult.Items = results.Item1;
        return reviewResult;
    }

    public ReviewPageableResult GetReviewsByZip(string productType, string serviceType, string zipCodes, int pageNumber, int itemsPerPage, string sortBy, string sortDirection)
    {
        var parameters = new List<SqlParameter>
        {
            new SqlParameter("ProductRefDescription", productType),
            new SqlParameter("ServiceRefDescription", serviceType),
            new SqlParameter("ZipCodes", zipCodes),
            new SqlParameter("PageNumber", pageNumber),
            new SqlParameter("ItemsPerPage", itemsPerPage),
            new SqlParameter("SortBy", sortBy),
            new SqlParameter("SortDirection", sortDirection)
        };
        var cmd = new SqlCommand("dbo.GetReviewsByZipCodes");
        cmd.Parameters.AddRange(parameters.ToArray());
        var results = ExecuteSqlReader(CreateReview, CreateReviewPageableResult, cmd, commandType: CommandType.StoredProcedure);
        var reviewResult = results.Item2.Single();
        reviewResult.Items = results.Item1;
        return reviewResult;
    }

    private Review CreateReview(IDataRecord record)
    {
        return new Review
        {
            PageReviewId = (int)record["PageReviewId"],
            ProductRefId = (Guid)record["ProductRefId"],
            ServiceTypeRefId = Convert.IsDBNull(record["ServiceTypeRefId"]) ? Guid.Empty : (Guid)record["ServiceTypeRefId"],
            TerritoryId = Convert.IsDBNull(record["TerritoryId"]) ? Guid.Empty : (Guid)record["TerritoryId"],
            FirstName = $"{record["FirstName"]}",
            LastName = $"{record["LastName"]}",
            City = $"{record["City"]}",
            State = $"{record["State"]}",
            Answer = $"{record["Answer"]}",
            Rating =(double)record["Rating"],
            SurveyDate = (DateTime)record["SurveyDate"]
        };
    }

    private ReviewPageableResult CreateReviewPageableResult(IDataRecord record)
    {
        return new ReviewPageableResult
        {
            AverageRating = (double)record["AverageRating"],
            Count1Stars = (int)record["Count1Stars"],
            Count2Stars = (int)record["Count2Stars"],
            Count3Stars = (int)record["Count3Stars"],
            Count4Stars = (int)record["Count4Stars"],
            Count5Stars = (int)record["Count5Stars"],
            ItemsPerPage = (int)record["ItemsPerPage"],
            PageNumber = (int)record["PageNumber"],
            TotalCount = (int)record["TotalCount"],
        };
    }
}
0
Pete Koelbl

私はsprocを呼び出し、オブジェクトで複数の結果セットを取得するため、最終的に

List<List<Dictionary<string, object>>>

MultiResultsSetでは、各結果セットは

List<Dictionary<string, object>>

タイプにキャスト sで、必要に応じてモデルに変換できます。

必要なものをすべて使用してsprocコマンドを設定したら、次のように渡します。

    private static List<List<Dictionary<string, object>>> ProcessReader(SqlCommand command)
    {
        var tables = new List<List<Dictionary<string, object>>>();
        using (var reader = command.ExecuteReader())
        {
            do
            {
                var table = new List<Dictionary<string, object>>();
                while (reader.Read())
                    table.Add(Read(reader));
                tables.Add(table);
            } while (reader.NextResult());
        }
        return tables;
    }

read（）はかなり簡単です。

    private static Dictionary<string, object> Read(IDataRecord reader)
    {
        var row = new Dictionary<string, object>();
        for (var i = 0; i < reader.FieldCount; i++)
        {
            var val = reader[i];
            row[reader.GetName(i)] = val == DBNull.Value ? null : val;
        }
        return row;
    }
0
Stephen Himes