OleDbCommand Class

Definition

Namespace:

System.Data.OleDb

Assembly:

System.Data.OleDb.dll

Package:

System.Data.OleDb v9.0.0

Source:

OleDbCommand.cs

Represents an SQL statement or stored procedure to execute against a data source.

public ref class OleDbCommand sealed : System::Data::Common::DbCommand, ICloneable, IDisposable

public sealed class OleDbCommand : System.Data.Common.DbCommand, ICloneable, IDisposable

type OleDbCommand = class
    inherit DbCommand
    interface IDbCommand
    interface IDisposable
    interface ICloneable

Public NotInheritable Class OleDbCommand
Inherits DbCommand
Implements ICloneable, IDisposable

Inheritance

Object

DbCommand

OleDbCommand

Implements

IDbCommand ICloneable IDisposable

Examples

The following example uses the OleDbCommand, along OleDbDataAdapter and OleDbConnection, to select rows from an Access database. The filled DataSet is then returned. The example is passed an initialized DataSet, a connection string, a query string that is an SQL SELECT statement, and a string that is the name of the source database table.

public void ReadMyData(string connectionString)
{
    string queryString = "SELECT OrderID, CustomerID FROM Orders";
    using (OleDbConnection connection = new OleDbConnection(connectionString))
    {
        OleDbCommand command = new OleDbCommand(queryString, connection);
        connection.Open();
        OleDbDataReader reader = command.ExecuteReader();

        while (reader.Read())
        {
            Console.WriteLine(reader.GetInt32(0) + ", " + reader.GetString(1));
        }
        // always call Close when done reading.
        reader.Close();
    }
}

Public Sub ReadMyData(ByVal connectionString As String)
    Dim queryString As String = "SELECT OrderID, CustomerID FROM Orders"
    Using connection As New OleDbConnection(connectionString)
        Dim command As New OleDbCommand(queryString, connection)

        connection.Open()

        Dim reader As OleDbDataReader = command.ExecuteReader()
        While reader.Read()
            Console.WriteLine(reader.GetInt32(0).ToString() + ", " _
               + reader.GetString(1))
        End While

        ' always call Close when done reading.
        reader.Close()
    End Using
End Sub

Remarks

When an instance of OleDbCommand is created, the read/write properties are set to their initial values. For a list of these values, see the OleDbCommand constructor.

OleDbCommand features the following methods executing commands at a data source:

Item	Description
ExecuteReader	Executes commands that return rows. ExecuteReader may not have the effect that you want if used to execute commands such as SQL SET statements.
ExecuteNonQuery	Executes commands such as SQL INSERT, DELETE, UPDATE, and SET statements.
ExecuteScalar	Retrieves a single value, for example, an aggregate value from a database.

You can reset the CommandText property and reuse the OleDbCommand object. However, you must close the OleDbDataReader before you can execute a new or previous command.

If a fatal OleDbException (for example, a SQL Server severity level of 20 or greater) is generated by the method executing an OleDbCommand, the OleDbConnection, the connection may be closed. However, the user can reopen the connection and continue.

Constructors

OleDbCommand()	Initializes a new instance of the OleDbCommand class.
OleDbCommand(String, OleDbConnection, OleDbTransaction)	Initializes a new instance of the OleDbCommand class with the text of the query, an OleDbConnection, and the Transaction.
OleDbCommand(String, OleDbConnection)	Initializes a new instance of the OleDbCommand class with the text of the query and an OleDbConnection.
OleDbCommand(String)	Initializes a new instance of the OleDbCommand class with the text of the query.

Properties

CommandText	Gets or sets the SQL statement or stored procedure to execute at the data source.
CommandTimeout	Gets or sets the wait time (in seconds) before terminating an attempt to execute a command and generating an error.
CommandType	Gets or sets a value that indicates how the CommandText property is interpreted.
Connection	Gets or sets the OleDbConnection used by this instance of the OleDbCommand.
DbConnection	Gets or sets the DbConnection used by this DbCommand. (Inherited from DbCommand)
DbParameterCollection	Gets the collection of DbParameter objects. (Inherited from DbCommand)
DbTransaction	Gets or sets the DbTransaction within which this DbCommand object executes. (Inherited from DbCommand)
DesignTimeVisible	Gets or sets a value that indicates whether the command object should be visible in a customized Windows Forms Designer control.
Parameters	Gets the OleDbParameterCollection.
Transaction	Gets or sets the OleDbTransaction within which the OleDbCommand executes.
UpdatedRowSource	Gets or sets how command results are applied to the DataRow when used by the Update method of the OleDbDataAdapter.

Methods

Cancel()	Tries to cancel the execution of an OleDbCommand.
Clone()	Creates a new OleDbCommand object that is a copy of the current instance.
CreateDbParameter()	Creates a new instance of a DbParameter object. (Inherited from DbCommand)
CreateParameter()	Creates a new instance of an OleDbParameter object.
Dispose()	Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources. (Inherited from DbCommand)
Dispose(Boolean)	Releases the unmanaged resources used by the DbCommand and optionally releases the managed resources. (Inherited from DbCommand)
DisposeAsync()	Asynchronously diposes the command object. (Inherited from DbCommand)
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
ExecuteDbDataReader(CommandBehavior)	Executes the command against its connection, returning a DbDataReader which can be used to access the results. (Inherited from DbCommand)
ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken)	Providers should implement this method to provide a non-default implementation for ExecuteReader overloads. The default implementation invokes the synchronous ExecuteReader() method and returns a completed task, blocking the calling thread. The default implementation will return a cancelled task if passed an already cancelled cancellation token. Exceptions thrown by ExecuteReader will be communicated via the returned Task Exception property. This method accepts a cancellation token that can be used to request the operation to be cancelled early. Implementations may ignore this request. (Inherited from DbCommand)
ExecuteNonQuery()	Executes an SQL statement against the Connection and returns the number of rows affected.
ExecuteNonQueryAsync()	An asynchronous version of ExecuteNonQuery(), which executes the command against its connection object, returning the number of rows affected. Invokes ExecuteNonQueryAsync(CancellationToken) with CancellationToken.None. (Inherited from DbCommand)
ExecuteNonQueryAsync(CancellationToken)	This is the asynchronous version of ExecuteNonQuery(). Providers should override with an appropriate implementation. The cancellation token may optionally be ignored. The default implementation invokes the synchronous ExecuteNonQuery() method and returns a completed task, blocking the calling thread. The default implementation will return a cancelled task if passed an already cancelled cancellation token. Exceptions thrown by ExecuteNonQuery() will be communicated via the returned Task Exception property. Do not invoke other methods and properties of the DbCommand object until the returned Task is complete. (Inherited from DbCommand)
ExecuteReader()	Sends the CommandText to the Connection and builds an OleDbDataReader.
ExecuteReader(CommandBehavior)	Sends the CommandText to the Connection, and builds an OleDbDataReader using one of the CommandBehavior values.
ExecuteReaderAsync()	An asynchronous version of ExecuteReader, which executes the command against its connection, returning a DbDataReader which can be used to access the results. Invokes ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken) with CancellationToken.None. (Inherited from DbCommand)
ExecuteReaderAsync(CancellationToken)	An asynchronous version of ExecuteReader, which executes the command against its connection, returning a DbDataReader which can be used to access the results. Invokes ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken). (Inherited from DbCommand)
ExecuteReaderAsync(CommandBehavior, CancellationToken)	Invokes ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken). (Inherited from DbCommand)
ExecuteReaderAsync(CommandBehavior)	An asynchronous version of ExecuteReader, which executes the command against its connection, returning a DbDataReader which can be used to access the results. Invokes ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken). (Inherited from DbCommand)
ExecuteScalar()	Executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.
ExecuteScalarAsync()	An asynchronous version of ExecuteScalar(), which executes the command and returns the first column of the first row in the first returned result set. All other columns, rows and result sets are ignored. Invokes ExecuteScalarAsync(CancellationToken) with CancellationToken.None. (Inherited from DbCommand)
ExecuteScalarAsync(CancellationToken)	This is the asynchronous version of ExecuteScalar(). Providers should override with an appropriate implementation. The cancellation token may optionally be ignored. The default implementation invokes the synchronous ExecuteScalar() method and returns a completed task, blocking the calling thread. The default implementation will return a cancelled task if passed an already cancelled cancellation token. Exceptions thrown by ExecuteScalar will be communicated via the returned Task Exception property. Do not invoke other methods and properties of the DbCommand object until the returned Task is complete. (Inherited from DbCommand)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Prepare()	Creates a prepared (or compiled) version of the command on the data source.
PrepareAsync(CancellationToken)	Asynchronously creates a prepared (or compiled) version of the command on the data source. (Inherited from DbCommand)
ResetCommandTimeout()	Resets the CommandTimeout property to the default value.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Explicit Interface Implementations

ICloneable.Clone()	For a description of this member, see Clone().
IDbCommand.ExecuteReader()	For a description of this member, see ExecuteReader().
IDbCommand.ExecuteReader(CommandBehavior)	Executes the CommandText against the Connection, and builds an IDataReader using one of the CommandBehavior values.

See also

• OleDbDataAdapter
• OleDbConnection
• Working with Commands