System.Data Namespace
Represents a parameter to a Command object, and optionally, its mapping to DataSet columns; and is implemented by .NET data providers that access data sources.
The IDataParameter interface allows an inheriting class to implement a Parameter class, which represents a parameter to a Command object. For more information about Parameter classes, see Using Stored Procedures with a Command. For more information about implementing .NET data providers, see Implementing a .NET Data Provider.
An application does not create an instance of the IDataParameter interface directly, but initializes an instance of a class that inherits IDataParameter.
Classes that inherit IDataParameter must implement the inherited members, and typically define additional members to add provider-specific functionality. For example, the IDataParameter interface defines the DbType property. In turn, the OleDbParameter class inherits this property, and also defines the OleDbType property.
Notes to Implementers: To promote consistency among .NET data providers, name the inheriting class in the form Prv Parameter where Prv is the uniform prefix given to all classes in a specific .NET data provider namespace. For example, Sql is the prefix of the SqlCommand class in the System.Data.SqlClient namespace.
When you inherit from the IDataParameter interface, you should implement the following constructors:
| Item |
Description |
| PrvParameter ( ) |
Initializes a new instance of the Parameter class. |
| PrvParameter ( string name, PrvDbType dataType ) |
Initializes a new instance of the Parameter class with the parameter name and data type. |
| PrvParameter ( string name, object value ) |
Initializes a new instance of the Parameter class with the parameter name and a Parameter object. |
| PrvParameter ( string name, PrvDbType dataType, int size ) |
Initializes a new instance of the Parameter class with the parameter name, data type, and width. |
| PrvParameter ( string name, PrvDbType dataType, int size, string srcColumn ) |
Initializes a new instance of the DbParameter class with the parameter name, data type, width, and source column name. |
| PrvParameter ( string parameterName, PrvDbType dbType, int size, ParameterDirection direction, Boolean isNullable, Byte precision, Byte scale, string srcColumn, DataRowVersion srcVersion, object value ) |
Initializes a new instance of the OleDbParameter class with the parameter name, data type, width, source column name, parameter direction, numeric precision, and other properties. |
The following example initializes multiple instances of the derived class, SqlParameter, through the SqlParameterCollection within the SqlDataAdapter. 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 SqlDataAdapter have already been created with the appropriate schema, commands, and connection.
void AddSqlParameters ( ) {
// ... create myDataSet and myDataAdapter ...
myDataAdapter.SelectCommand.Parameters.Add
( "@CategoryName", SqlDbType.VarChar, 80 ).Value = "toasters";
myDataAdapter.SelectCommand.Parameters.Add
( "@SerialNum", SqlDbType.Int ).Value = 239;
myDataAdapter.Fill ( myDataSet );
}
Public Sub AddSqlParameters ( )
' ... create myDataSet and myDataAdapter ...
myDataAdapter.SelectCommand.Parameters.Add _
( "@CategoryName", SqlDbType.VarChar, 80 ).Value = "toasters"
myDataAdapter.SelectCommand.Parameters.Add _
( "@SerialNum", SqlDbType.Int ).Value = 239
myDataAdapter.Fill ( myDataSet )
End Sub |
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VB |
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