How to Add Constraints to the Host File Dataset

The HostFileDataAdapter.Fill method fills a DataSet object with table columns and rows from a data source; though constraints are commonly set by the data source, the Fill method does not add this schema information to the DataSet object by default. To populate a DataSet object with existing primary key constraint information from a data source, you can call HostFileDataAdapter.FillSchema.

Note

If a column in a data source is identified as auto-incrementing, the FillSchema method, or the Fill method with a MissingSchemaAction of AddWithKey, creates a DataColumn that has an AutoIncrement property set to true. However, you must set the AutoIncrementStep and AutoIncrementSeed values yourself.

To populate a dataset with additional key constraints

1. Call HostFileDataAdapter.FillSchema, using the targeted DataSet and Schema that contains the specified key constraints.

   Adding schema information to a DataSet before filling it with data ensures that primary key constraints are included with the DataTable objects in the DataSet object. As a result, when additional calls to fill the DataSet are made, the primary key column information is used to match new rows from the data source with current rows in each DataTable object, and current data in the tables is overwritten with data from the data source. Without the schema information, the new rows from the data source are appended to the DataSet object, resulting in duplicate rows.

See Also

Working with the Host File Adapter and Dataset
BizTalk Adapter for Host Files Configuration