Можно ли выполнить несколько запросов и вернуть их результаты, выполняющие SqlCommand только один раз?
Как вернуть несколько наборов результатов с помощью SqlCommand?
Ответ 1
См. SqlDataReader.NextResult (SqlDataReader возвращается из вызова SqlCommand.ExecuteReader):
Продвигает средство чтения данных к следующему результату [set] при чтении результатов пакетных операторов Transact-SQL.
Пример:
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"]
});
}
}
}
}
Другие примеры:
Ответ 2
Создайте Stored Procedure, который имеет несколько выборок, и заполните DataSet.
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;
}
Возвращенный набор данных будет содержать DataTable в нем Таблица для каждого выбора в хранимой процедуре.
Ответ 3
Такие инструменты, как "dapper", делают это очень легко, независимо от того, используете ли вы специальные текстовые запросы или хранимые процедуры; например:
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
}
Отдельные сетки также можно читать без буферизации (как открытый IEnumerable<T> поверх самого считывателя) с помощью необязательных параметров до Read[<T>].
Ответ 4
Попробуйте это
Dim dt1, dt2, dt3As New DataTable
Dim command As SqlCommand
Dim adapter As New SqlDataAdapter
Dim ds As New DataSet
Dim Sql1, Sql2, Sql3 As String
Sql1 = "select id, CurName from Table1 where IS_Deleted=0 order by id"
Sql2 = "select id ,Item from Table2 order by id"
Sql3 = "select id ,SellPrice from Table3 order by id"
Try
conn1.Open()
command = New SqlCommand(Sql1, conn1)
command.CommandType = CommandType.Text
adapter.SelectCommand = command
adapter.Fill(ds, "dt1")
adapter.SelectCommand.CommandText = Sql2
adapter.Fill(ds, "dt2")
adapter.SelectCommand.CommandText = Sql3
adapter.Fill(ds, "dt3")
adapter.Dispose()
command.Dispose()
conn1.Close()
cmbCurrency.DataSource = ds.Tables("dt1")
cmbCurrency.DisplayMember = "CurName"
cmbCurrency.ValueMember = "id"
cmbCurrency.SelectedIndex = -1
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
cmbGroups.DataSource = ds.Tables("dt2")
cmbGroups.DisplayMember = "Item"
cmbGroups.ValueMember = "id"
cmbGroups.SelectedIndex = -1
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
cmbUnits.DataSource = ds.Tables("dt3")
cmbUnits.DisplayMember = "SellPrice"
cmbUnits.ValueMember = "id"
cmbUnits.SelectedIndex = -1
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
Catch ex As Exception
MessageBox.Show(ex.ToString())
End Try
Для получения дополнительной помощи http://vb.net-informations.com/dataset/dataset-multiple-tables-sqlserver.htm
Ответ 5
Это то, что я использовал для возврата нескольких наборов результатов.
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();
}
}
Тогда я просто наследую его так:
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"],
};
}
}
Ответ 6
Я вызываю sproc и получаю множество результирующих множеств с объектом, поэтому вы получаете
List<List<Dictionary<string, object>>>
В multResultsSet каждый набор результатов затем
List<Dictionary<string, object>>
Их можно отливать по типу и при необходимости преобразовывать в модели.
После того, как вы настроили команду sproc всем необходимым, перейдите к следующему:
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;
}
и Read() довольно прямолинейно.
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;
}