April 2003
Beginner to intermediate
620 pages
21h 48m
English
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Retrieving Schema Information from the Data Source
Schema information can be retrieved
from a data source using the FillSchema( )
method, which retrieves the schema
information for the SQL statement in the
SelectCommand. The method adds a
DataTable to the DataSet and
adds DataColumn objects to that table. Finally, it
configures the AllowDBNull,
AutoIncrement, MaxLength,
ReadOnly, and Unique properties
of the DataColumn, based on the data source. While
it configures the AutoIncrement property, it
doesn’t set the AutoIncrementSeed
and AutoIncrementStep properties. The
FillSchema( ) method also configures the primary
key and unique constraints for the DataTable. It
doesn’t configure the
DefaultValue property.
In addition to an argument specifying the DataSet
argument, the FillSchema( ) method takes an
argument specifying whether the schema is transformed by the table
mappings for the data adapter. Mapping tables and columns is
discussed in more detail later in this chapter
If the FillSchema( ) method is used with a table
that already has schema defined, the original schema
isn’t overwritten. Rather, new columns are added if
they are part of the schema retrieved but don’t
exist in the table.
Finally, if a query returning multiple result sets is specified in
the SelectCommand, only the schema from the first
result set is used. To fill schemas based on queries with multiple
result sets, use the Fill( ) method with the
MissingSchemaAction set to
AddWithKey.
The following example demonstrates ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.