SqlCommand 类
定义
重要
一些信息与预发行产品相关,相应产品在发行之前可能会进行重大修改。 对于此处提供的信息,Microsoft 不作任何明示或暗示的担保。
表示要对 SQL Server 数据库执行的一个 Transact-SQL 语句或存储过程。 此类不能被继承。
public ref class SqlCommand sealed : System::Data::Common::DbCommand, ICloneable
public ref class SqlCommand sealed : System::Data::Common::DbCommand
public ref class SqlCommand sealed : System::ComponentModel::Component, ICloneable, IDisposable, System::Data::IDbCommand
public ref class SqlCommand sealed : System::Data::Common::DbCommand, ICloneable, IDisposable
public sealed class SqlCommand : System.Data.Common.DbCommand, ICloneable
public sealed class SqlCommand : System.Data.Common.DbCommand
public sealed class SqlCommand : System.ComponentModel.Component, ICloneable, IDisposable, System.Data.IDbCommand
public sealed class SqlCommand : System.Data.Common.DbCommand, ICloneable, IDisposable
type SqlCommand = class
inherit DbCommand
interface ICloneable
type SqlCommand = class
inherit DbCommand
type SqlCommand = class
inherit Component
interface IDbCommand
interface IDisposable
interface ICloneable
type SqlCommand = class
inherit DbCommand
interface IDbCommand
interface ICloneable
interface IDisposable
Public NotInheritable Class SqlCommand
Inherits DbCommand
Implements ICloneable
Public NotInheritable Class SqlCommand
Inherits DbCommand
Public NotInheritable Class SqlCommand
Inherits Component
Implements ICloneable, IDbCommand, IDisposable
Public NotInheritable Class SqlCommand
Inherits DbCommand
Implements ICloneable, IDisposable
- 继承
- 继承
- 继承
- 实现
示例
以下示例创建一个 SqlConnection、一个 SqlCommand和一个 SqlDataReader。 该示例读取数据,并将其写入控制台。 最后,该示例关闭 SqlDataReader 代码块,然后在 SqlConnection 退出 Using
代码块时关闭该示例。
private static void ReadOrderData(string connectionString)
{
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection = new SqlConnection(
connectionString))
{
SqlCommand command = new SqlCommand(
queryString, connection);
connection.Open();
using(SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader[0], reader[1]));
}
}
}
}
Public Sub ReadOrderData(ByVal connectionString As String)
Dim queryString As String = _
"SELECT OrderID, CustomerID FROM dbo.Orders;"
Using connection As New SqlConnection(connectionString)
Dim command As New SqlCommand(queryString, connection)
connection.Open()
Dim reader As SqlDataReader = command.ExecuteReader()
Try
While reader.Read()
Console.WriteLine(String.Format("{0}, {1}", _
reader(0), reader(1)))
End While
Finally
' Always call Close when done reading.
reader.Close()
End Try
End Using
End Sub
以下示例演示如何创建和执行不同类型的 SqlCommand 对象。
首先,必须通过执行以下脚本来创建示例数据库:
USE [master]
GO
CREATE DATABASE [MySchool]
GO
USE [MySchool]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE procedure [dbo].[CourseExtInfo] @CourseId int
as
select c.CourseID,c.Title,c.Credits,d.Name as DepartmentName
from Course as c left outer join Department as d on c.DepartmentID=d.DepartmentID
where c.CourseID=@CourseId
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
create procedure [dbo].[DepartmentInfo] @DepartmentId int,@CourseCount int output
as
select @CourseCount=Count(c.CourseID)
from course as c
where c.DepartmentID=@DepartmentId
select d.DepartmentID,d.Name,d.Budget,d.StartDate,d.Administrator
from Department as d
where d.DepartmentID=@DepartmentId
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
Create PROCEDURE [dbo].[GetDepartmentsOfSpecifiedYear]
@Year int,@BudgetSum money output
AS
BEGIN
SELECT @BudgetSum=SUM([Budget])
FROM [MySchool].[dbo].[Department]
Where YEAR([StartDate])=@Year
SELECT [DepartmentID]
,[Name]
,[Budget]
,[StartDate]
,[Administrator]
FROM [MySchool].[dbo].[Department]
Where YEAR([StartDate])=@Year
END
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Course]([CourseID] [nvarchar](10) NOT NULL,
[Year] [smallint] NOT NULL,
[Title] [nvarchar](100) NOT NULL,
[Credits] [int] NOT NULL,
[DepartmentID] [int] NOT NULL,
CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED
(
[CourseID] ASC,
[Year] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Department]([DepartmentID] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NOT NULL,
[Budget] [money] NOT NULL,
[StartDate] [datetime] NOT NULL,
[Administrator] [int] NULL,
CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED
(
[DepartmentID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Person]([PersonID] [int] IDENTITY(1,1) NOT NULL,
[LastName] [nvarchar](50) NOT NULL,
[FirstName] [nvarchar](50) NOT NULL,
[HireDate] [datetime] NULL,
[EnrollmentDate] [datetime] NULL,
CONSTRAINT [PK_School.Student] PRIMARY KEY CLUSTERED
(
[PersonID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[StudentGrade]([EnrollmentID] [int] IDENTITY(1,1) NOT NULL,
[CourseID] [nvarchar](10) NOT NULL,
[StudentID] [int] NOT NULL,
[Grade] [decimal](3, 2) NOT NULL,
CONSTRAINT [PK_StudentGrade] PRIMARY KEY CLUSTERED
(
[EnrollmentID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
create view [dbo].[EnglishCourse]
as
select c.CourseID,c.Title,c.Credits,c.DepartmentID
from Course as c join Department as d on c.DepartmentID=d.DepartmentID
where d.Name=N'English'
GO
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C1045', 2012, N'Calculus', 4, 7)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C1061', 2012, N'Physics', 4, 1)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C2021', 2012, N'Composition', 3, 2)
INSERT [dbo].[Course] ([CourseID], [Year], [Title], [Credits], [DepartmentID]) VALUES (N'C2042', 2012, N'Literature', 4, 2)
SET IDENTITY_INSERT [dbo].[Department] ON
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (1, N'Engineering', 350000.0000, CAST(0x0000999C00000000 AS DateTime), 2)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (2, N'English', 120000.0000, CAST(0x0000999C00000000 AS DateTime), 6)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (4, N'Economics', 200000.0000, CAST(0x0000999C00000000 AS DateTime), 4)
INSERT [dbo].[Department] ([DepartmentID], [Name], [Budget], [StartDate], [Administrator]) VALUES (7, N'Mathematics', 250024.0000, CAST(0x0000999C00000000 AS DateTime), 3)
SET IDENTITY_INSERT [dbo].[Department] OFF
SET IDENTITY_INSERT [dbo].[Person] ON
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (1, N'Hu', N'Nan', NULL, CAST(0x0000A0BF00000000 AS DateTime))
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (2, N'Norman', N'Laura', NULL, CAST(0x0000A0BF00000000 AS DateTime))
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (3, N'Olivotto', N'Nino', NULL, CAST(0x0000A0BF00000000 AS DateTime))
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (4, N'Anand', N'Arturo', NULL, CAST(0x0000A0BF00000000 AS DateTime))
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (5, N'Jai', N'Damien', NULL, CAST(0x0000A0BF00000000 AS DateTime))
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (6, N'Holt', N'Roger', CAST(0x000097F100000000 AS DateTime), NULL)
INSERT [dbo].[Person] ([PersonID], [LastName], [FirstName], [HireDate], [EnrollmentDate]) VALUES (7, N'Martin', N'Randall', CAST(0x00008B1A00000000 AS DateTime), NULL)
SET IDENTITY_INSERT [dbo].[Person] OFF
SET IDENTITY_INSERT [dbo].[StudentGrade] ON
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (1, N'C1045', 1, CAST(3.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (2, N'C1045', 2, CAST(3.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (3, N'C1045', 3, CAST(2.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (4, N'C1045', 4, CAST(4.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (5, N'C1045', 5, CAST(3.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (6, N'C1061', 1, CAST(4.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (7, N'C1061', 3, CAST(3.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (8, N'C1061', 4, CAST(2.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (9, N'C1061', 5, CAST(1.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (10, N'C2021', 1, CAST(2.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (11, N'C2021', 2, CAST(3.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (12, N'C2021', 4, CAST(3.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (13, N'C2021', 5, CAST(3.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (14, N'C2042', 1, CAST(2.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (15, N'C2042', 2, CAST(3.50 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (16, N'C2042', 3, CAST(4.00 AS Decimal(3, 2)))
INSERT [dbo].[StudentGrade] ([EnrollmentID], [CourseID], [StudentID], [Grade]) VALUES (17, N'C2042', 5, CAST(3.00 AS Decimal(3, 2)))
SET IDENTITY_INSERT [dbo].[StudentGrade] OFF
ALTER TABLE [dbo].[Course] WITH CHECK ADD CONSTRAINT [FK_Course_Department] FOREIGN KEY([DepartmentID])
REFERENCES [dbo].[Department] ([DepartmentID])
GO
ALTER TABLE [dbo].[Course] CHECK CONSTRAINT [FK_Course_Department]
GO
ALTER TABLE [dbo].[StudentGrade] WITH CHECK ADD CONSTRAINT [FK_StudentGrade_Student] FOREIGN KEY([StudentID])
REFERENCES [dbo].[Person] ([PersonID])
GO
ALTER TABLE [dbo].[StudentGrade] CHECK CONSTRAINT [FK_StudentGrade_Student]
GO
接下来,编译并执行以下内容:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Threading.Tasks;
class Program {
static class SqlHelper {
// Set the connection, command, and then execute the command with non query.
public static Int32 ExecuteNonQuery(String connectionString, String commandText,
CommandType commandType, params SqlParameter[] parameters) {
using (SqlConnection conn = new SqlConnection(connectionString)) {
using (SqlCommand cmd = new SqlCommand(commandText, conn)) {
// There're three command types: StoredProcedure, Text, TableDirect. The TableDirect
// type is only for OLE DB.
cmd.CommandType = commandType;
cmd.Parameters.AddRange(parameters);
conn.Open();
return cmd.ExecuteNonQuery();
}
}
}
// Set the connection, command, and then execute the command and only return one value.
public static Object ExecuteScalar(String connectionString, String commandText,
CommandType commandType, params SqlParameter[] parameters) {
using (SqlConnection conn = new SqlConnection(connectionString)) {
using (SqlCommand cmd = new SqlCommand(commandText, conn)) {
cmd.CommandType = commandType;
cmd.Parameters.AddRange(parameters);
conn.Open();
return cmd.ExecuteScalar();
}
}
}
// Set the connection, command, and then execute the command with query and return the reader.
public static SqlDataReader ExecuteReader(String connectionString, String commandText,
CommandType commandType, params SqlParameter[] parameters) {
SqlConnection conn = new SqlConnection(connectionString);
using (SqlCommand cmd = new SqlCommand(commandText, conn)) {
cmd.CommandType = commandType;
cmd.Parameters.AddRange(parameters);
conn.Open();
// When using CommandBehavior.CloseConnection, the connection will be closed when the
// IDataReader is closed.
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
return reader;
}
}
}
static void Main(string[] args) {
String connectionString = "Data Source=(local);Initial Catalog=MySchool;Integrated Security=True;Asynchronous Processing=true;";
CountCourses(connectionString, 2012);
Console.WriteLine();
Console.WriteLine("Following result is the departments that started from 2007:");
GetDepartments(connectionString, 2007);
Console.WriteLine();
Console.WriteLine("Add the credits when the credits of course is lower than 4.");
AddCredits(connectionString, 4);
Console.WriteLine();
Console.WriteLine("Please press any key to exit...");
Console.ReadKey();
}
static void CountCourses(String connectionString, Int32 year) {
String commandText = "Select Count([CourseID]) FROM [MySchool].[dbo].[Course] Where Year=@Year";
SqlParameter parameterYear = new SqlParameter("@Year", SqlDbType.Int);
parameterYear.Value = year;
Object oValue = SqlHelper.ExecuteScalar(connectionString, commandText, CommandType.Text, parameterYear);
Int32 count;
if (Int32.TryParse(oValue.ToString(), out count))
Console.WriteLine("There {0} {1} course{2} in {3}.", count > 1 ? "are" : "is", count, count > 1 ? "s" : null, year);
}
// Display the Departments that start from the specified year.
static void GetDepartments(String connectionString, Int32 year) {
String commandText = "dbo.GetDepartmentsOfSpecifiedYear";
// Specify the year of StartDate
SqlParameter parameterYear = new SqlParameter("@Year", SqlDbType.Int);
parameterYear.Value = year;
// When the direction of parameter is set as Output, you can get the value after
// executing the command.
SqlParameter parameterBudget = new SqlParameter("@BudgetSum", SqlDbType.Money);
parameterBudget.Direction = ParameterDirection.Output;
using (SqlDataReader reader = SqlHelper.ExecuteReader(connectionString, commandText,
CommandType.StoredProcedure, parameterYear, parameterBudget)) {
Console.WriteLine("{0,-20}{1,-20}{2,-20}{3,-20}", "Name", "Budget", "StartDate",
"Administrator");
while (reader.Read()) {
Console.WriteLine("{0,-20}{1,-20:C}{2,-20:d}{3,-20}", reader["Name"],
reader["Budget"], reader["StartDate"], reader["Administrator"]);
}
}
Console.WriteLine("{0,-20}{1,-20:C}", "Sum:", parameterBudget.Value);
}
// If credits of course is lower than the certain value, the method will add the credits.
static void AddCredits(String connectionString, Int32 creditsLow) {
String commandText = "Update [MySchool].[dbo].[Course] Set Credits=Credits+1 Where Credits<@Credits";
SqlParameter parameterCredits = new SqlParameter("@Credits", creditsLow);
Int32 rows = SqlHelper.ExecuteNonQuery(connectionString, commandText, CommandType.Text, parameterCredits);
Console.WriteLine("{0} row{1} {2} updated.", rows, rows > 1 ? "s" : null, rows > 1 ? "are" : "is");
}
}
注解
创建实例 SqlCommand 时,读/写属性将设置为其初始值。 有关这些值的列表,请参阅 SqlCommand 构造函数。
SqlCommand在SQL Server数据库中执行命令的方法如下:
项 | 说明 |
---|---|
BeginExecuteNonQuery | 启动由此SqlCommand描述的 Transact-SQL 语句或存储过程的异步执行,通常执行 INSERT、DELETE、UPDATE 和 SET 语句等命令。 要调用的每个调用都必须与完成操作的调用BeginExecuteNonQueryEndExecuteNonQuery配对,通常位于单独的线程上。 |
BeginExecuteReader | 启动由此描述SqlCommand的 Transact-SQL 语句或存储过程的异步执行,并从服务器检索一个或多个结果集。 要调用的每个调用都必须与完成操作的调用BeginExecuteReaderEndExecuteReader配对,通常位于单独的线程上。 |
BeginExecuteXmlReader | 启动此 SqlCommand 描述的 Transact-SQL 语句或存储过程的异步执行。 要调用的每个调用都必须与调用配对,该调用BeginExecuteXmlReader``EndExecuteXmlReader 完成操作(通常位于单独的线程上)并返回对象XmlReader。 |
ExecuteReader | 执行返回行的命令。 为了提高性能,ExecuteReader请使用 Transact-SQL sp_executesql 系统存储过程调用命令。 因此,如果用于执行 Transact-SQL SET 语句等命令,ExecuteReader则可能没有所需的效果。 |
ExecuteNonQuery | 执行 Transact-SQL INSERT、DELETE、UPDATE 和 SET 语句等命令。 |
ExecuteScalar | 检索单个值 (例如,从数据库) 聚合值。 |
ExecuteXmlReader | 将 CommandText 发送到 Connection,并生成一个 XmlReader 对象。 |
可以重置 CommandText 属性并重复使用 SqlCommand 该对象。 但是,必须先关闭 SqlDataReader 才能执行新的或上一个命令。
如果由执行 a 的方法生成,SqlExceptionSqlCommand则当严重级别为 19 或更少时,该SqlConnection级别将保持打开状态。 当严重级别为 20 或更大时,服务器通常会关闭该 SqlConnection级别。 但是,用户可以重新打开连接并继续操作。
备注
.NET Framework数据提供程序不支持无名称(也称为序号)参数SQL Server。
构造函数
SqlCommand() |
初始化 SqlCommand 类的新实例。 |
SqlCommand(String) |
使用查询的文本初始化 SqlCommand 类的新实例。 |
SqlCommand(String, SqlConnection) |
使用查询的文本和 SqlConnection 初始化 SqlCommand 类的新实例。 |
SqlCommand(String, SqlConnection, SqlTransaction) |
使用查询文本、SqlConnection 以及 SqlTransaction 初始化 SqlCommand 类的新实例。 |
SqlCommand(String, SqlConnection, SqlTransaction, SqlCommandColumnEncryptionSetting) |
使用指定的命令文本、连接、事务和加密设置初始化 SqlCommand 类的新实例。 |
属性
方法
事件
Disposed |
在通过调用 Dispose() 方法释放组件时发生。 (继承自 Component) |
StatementCompleted |
当 Transact-SQL 语句执行完成时发生。 |
显式接口实现
ICloneable.Clone() |
创建是当前实例的副本的新 SqlCommand 对象。 |
IDbCommand.Connection |
获取或设置 IDbCommand 的此实例使用的 IDbConnection。 (继承自 DbCommand) |
IDbCommand.CreateParameter() |
创建 SqlParameter 对象的新实例。 |
IDbCommand.CreateParameter() |
创建 IDbDataParameter 对象的新实例。 (继承自 DbCommand) |
IDbCommand.ExecuteReader() |
将 CommandText 发送到 Connection,并生成一个 SqlDataReader。 |
IDbCommand.ExecuteReader() |
对 Connection 执行 CommandText 并生成 IDataReader。 (继承自 DbCommand) |
IDbCommand.ExecuteReader(CommandBehavior) |
将 CommandText 发送到 Connection,并使用 CommandBehavior 值之一生成 SqlDataReader。 |
IDbCommand.ExecuteReader(CommandBehavior) |
对 Connection 执行 CommandText,并使用 CommandBehavior 值之一生成 IDataReader。 (继承自 DbCommand) |
IDbCommand.Parameters | (继承自 DbCommand) |
IDbCommand.Transaction |
获取或设置将在其中执行此 DbCommand 对象的 DbTransaction。 (继承自 DbCommand) |