OleDbParameter Class

Definition

Represents a parameter to an OleDbCommand and optionally its mapping to a DataSet column. This class cannot be inherited.

public ref class OleDbParameter sealed : System::Data::Common::DbParameter, ICloneable
[System.ComponentModel.TypeConverter(typeof(System.Data.OleDb.OleDbParameter/OleDbParameterConverter))]
[System.ComponentModel.TypeConverter(typeof(System.Data.OleDb.OleDbParameterConverter))]
public sealed class OleDbParameter : System.Data.Common.DbParameter, ICloneable
type OleDbParameter = class
    inherit DbParameter
    interface ICloneable
    interface IDbDataParameter
    interface IDataParameter
Public NotInheritable Class OleDbParameter
Inherits DbParameter
Implements ICloneable
Inheritance
OleDbParameter
Attributes
Implements

Examples

The following example creates multiple instances of OleDbParameter through the OleDbParameterCollection collection within the OleDbDataAdapter. These parameters are used to select data from the data source and place the data in the DataSet. This example assumes that a DataSet and an OleDbDataAdapter have already been created by using the appropriate schema, commands, and connection.

public DataSet GetDataSetFromAdapter(
    DataSet dataSet, string connectionString, string queryString)
{
    using (OleDbConnection connection =
               new OleDbConnection(connectionString))
    {
        OleDbDataAdapter adapter =
            new OleDbDataAdapter(queryString, connection);

        // Set the parameters.
        adapter.SelectCommand.Parameters.Add(
            "@CategoryName", OleDbType.VarChar, 80).Value = "toasters";
        adapter.SelectCommand.Parameters.Add(
            "@SerialNum", OleDbType.Integer).Value = 239;

        // Open the connection and fill the DataSet.
        try
        {
            connection.Open();
            adapter.Fill(dataSet);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        // The connection is automatically closed when the
        // code exits the using block.
    }
    return dataSet;
}
Public Function GetDataSetFromAdapter( _
    ByVal dataSet As DataSet, ByVal connectionString As String, _
    ByVal queryString As String) As DataSet

    Using connection As New OleDbConnection(connectionString)
        Dim adapter As New OleDbDataAdapter(queryString, connection)

        ' Set the parameters.
        adapter.SelectCommand.Parameters.Add( _
            "@CategoryName", OleDbType.VarChar, 80).Value = "toasters"
        adapter.SelectCommand.Parameters.Add( _
         "@SerialNum", OleDbType.Integer).Value = 239

        ' Open the connection and fill the DataSet.
        Try
            connection.Open()
            adapter.Fill(dataSet)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
        ' The connection is automatically closed when the
        ' code exits the Using block.
    End Using

    Return dataSet
End Function

Remarks

The OLE DB.NET Framework Data Provider uses positional parameters that are marked with a question mark (?) instead of named parameters.

When querying an Oracle database using the Microsoft OLE DB Provider for Oracle (MSDAORA) and the OLE DB.NET Framework Data Provider, using the LIKE clause to query values in fixed-length fields may not return all expected matches. The reason is that when Oracle matches values for fixed-length fields in a LIKE clause, it matches the entire length of the string, including any padding trailing spaces. For example, if a table in an Oracle database contains a field named "Field1" that is defined as char(3), and you enter the value "a" into a row of that table, the following code does not return the row.

Dim queryString As String = "SELECT * FROM Table1 WHERE Field1 LIKE ?"  
Dim command As OleDbCommand = New OleDbCommand(queryString, connection)  
command.Parameters.Add("@p1", OleDbType.Char, 3).Value = "a"  
Dim reader As OleDbDataReader = command.ExecuteReader()  
string queryString = "SELECT * FROM Table1 WHERE Field1 LIKE ?";  
OleDbCommand command = new OleDbCommand(queryString, connection);  
command.Parameters.Add("@p1", OleDbType.Char, 3).Value = "a";  
OleDbDataReader reader = command.ExecuteReader();  

This is because Oracle stores the column value as "a " (padding "a", with trailing spaces, to the fixed field length of 3), which Oracle does not treat as a match for the parameter value of "a" in the case of a LIKE comparison of fixed-length fields.

To resolve this problem, append a percentage ("%") wildcard character to the parameter value ("a%"), or use an SQL = comparison instead.

Constructors

OleDbParameter()

Initializes a new instance of the OleDbParameter class.

OleDbParameter(String, Object)

Initializes a new instance of the OleDbParameter class that uses the parameter name and the value of the new OleDbParameter.

OleDbParameter(String, OleDbType)

Initializes a new instance of the OleDbParameter class that uses the parameter name and data type.

OleDbParameter(String, OleDbType, Int32)

Initializes a new instance of the OleDbParameter class that uses the parameter name, data type, and length.

OleDbParameter(String, OleDbType, Int32, ParameterDirection, Boolean, Byte, Byte, String, DataRowVersion, Object)

Initializes a new instance of the OleDbParameter class that uses the parameter name, data type, length, source column name, parameter direction, numeric precision, and other properties.

OleDbParameter(String, OleDbType, Int32, ParameterDirection, Byte, Byte, String, DataRowVersion, Boolean, Object)

Initializes a new instance of the OleDbParameter class that uses the parameter name, data type, length, source column name, parameter direction, numeric precision, and other properties.

OleDbParameter(String, OleDbType, Int32, String)

Initializes a new instance of the OleDbParameter class that uses the parameter name, data type, length, and source column name.

Properties

DbType

Gets or sets the DbType of the parameter.

Direction

Gets or sets a value that indicates whether the parameter is input-only, output-only, bidirectional, or a stored procedure return-value parameter.

IsNullable

Gets or sets a value that indicates whether the parameter accepts null values.

Offset
OleDbType

Gets or sets the OleDbType of the parameter.

ParameterName

Gets or sets the name of the OleDbParameter.

Precision

Gets or sets the maximum number of digits used to represent the Value property.

Scale

Gets or sets the number of decimal places to which Value is resolved.

Size

Gets or sets the maximum size, in bytes, of the data within the column.

SourceColumn

Gets or sets the name of the source column mapped to the DataSet and used for loading or returning the Value.

SourceColumnNullMapping

Sets or gets a value which indicates whether the source column is nullable. This allows DbCommandBuilder to correctly generate Update statements for nullable columns.

SourceVersion

Gets or sets the DataRowVersion to use when you load Value.

Value

Gets or sets the value of the parameter.

Methods

CreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.

(Inherited from MarshalByRefObject)
Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetLifetimeService()

Retrieves the current lifetime service object that controls the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
InitializeLifetimeService()

Obtains a lifetime service object to control the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
MemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.

(Inherited from MarshalByRefObject)
ResetDbType()

Resets the type associated with this OleDbParameter.

ResetOleDbType()

Resets the type associated with this OleDbParameter.

ToString()

Gets a string that contains the ParameterName.

Explicit Interface Implementations

ICloneable.Clone()

For a description of this member, see Clone().

Applies to

See also