Name
MissingSchemaAction
Synopsis
This enumeration specifies what happens when adding information to a
DataSet
and the schema information
can’t be found. This enumeration is used when
merging two DataSet
objects (with the
DataSet.Merge( )
method) and when filling a
DataSet
from a data source using the
IDataAdapter.Fill( )
method. In the first case, a
MissingSchemaAction
value is specified as a
parameter. In the second case, a
MissingSchemaAction
value is set using the
IDataAdapter.MissingSchemaAction
property.
If set to Add
, the new missing
DataColumn
objects are added to the
DataSet
. If set to AddWithKey
(the default when filling a DataSet
), the
required DataColumn
objects are added, and ADO.NET
tries to determine the primary key. In the case of the SQL Server
provider, this involves appending the FOR BROWSE clause on the SQL
statement and parsing out the additional information. In the case of
an OLE DB provider, this involves setting the
DBPROP_UNIQUEROWS
property, and then determining
which columns are primary key columns by examining
DBCOLUMN_KEYCOLUMN
in the
IColumnsRowset
. (Not all OLE DB providers support
this technique. If you experience problems, use
Add
instead of AddWithKey
and
set the primary key manually.) Finally, you can specify
Ignore
, in which case data in a missing column
will not be added, or Error
, in which case a
System.SystemException
is thrown if data is
encountered for a column that doesn’t exist.
public enum MissingSchemaAction { Add = 1, Ignore = 2, Error = ...
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