DbDataAdapter.Fill Method (DataTable, IDbCommand, CommandBehavior)
Assembly: System.Data (in System.Data.dll)
protected virtual int Fill( DataTable dataTable, IDbCommand command, CommandBehavior behavior )
- Type: System.Data.IDbCommand
The SQL SELECT statement used to retrieve rows from the data source.
The Fill method retrieves rows from the data source using the SELECT statement specified by an associated SelectCommand property. The connection object associated with the SELECT statement must be valid, but it does not need to be open. If the connection is closed before Fill is called, it is opened to retrieve data and then closed. If the connection is open before Fill is called, it remains open.
The Fill operation then adds the rows to the specified destination DataTable object in the DataSet, creating the DataTable object if it does not already exist. When creating a DataTable object, the Fill operation normally creates only column name metadata. However, if the MissingSchemaAction property is set to AddWithKey, appropriate primary keys and constraints are also created.
If the DbDataAdapter object encounters duplicate columns while populating a DataTable, it will generate names for the subsequent columns, using the pattern "columnname1", "columnname2", "columnname3", and so on. If the incoming data contains unnamed columns, they are placed in the DataSet according to the pattern "Column1", "Column2", and so on.
You can use the Fill method multiple times on the same DataTable. If a primary key exists, incoming rows are merged with matching rows that already exist. If no primary key exists, incoming rows are appended to the DataTable.
If the SelectCommand returns the results of an OUTER JOIN, the DataAdapter does not set a PrimaryKey value for the resulting DataTable. You must explicitly define the primary key to ensure that duplicate rows are resolved correctly. For more information, see Defining Primary Keys.
When handling batch SQL statements that return multiple results, the implementation of FillSchema for the .NET Framework Data Provider for OLE DB retrieves schema information for only the first result. To retrieve schema information for multiple results, use Fill with the MissingSchemaAction set to AddWithKey.
This overload of the Fill method is protected and is designed for use by a .NET Framework data provider.