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by Tim Sneath.
Original Post: ADO.NET Tips & Tricks - Part I
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This is either (a) the start of an occasional series discussing ways to get the most
out of ADO.NET, or (b) Tim writing up a series of notes he made while reading Microsoft
ADO.NET Core Reference - you decide!
If you're trying to create an OLE DB connection string to use with an OleDbConnection object,
create an empty file with a .UDL extension on the desktop (e.g. copy nul conn.udl),
and then double-click on it. Use the user interface to configure the connection, and
then open the .UDL file up in Notepad. Bingo - a fully-populated connection string!
Details of all the provider-specific connection properties can be found in the MDAC
SDK.
Rather than creating a new SqlCommand object
and passing it a connection as a parameter to the constructor, why not simply call
the SqlConnection.CreateCommand() method
for the sake of simplicity? The C# using keyword
can be applied to this to allow the object to be auto-disposed when finished with.
Speed up the performance of DataReader queries
by (i) using ordinals to specify the column name (you can identify the specific ordinal
with the GetOrdinal() method),
and (ii) using a type-specific GetX() method
rather than an indexer to retrieve the column contents. Thus myReader.GetString(0) rather
than myReader["custName"].
When a row is updated, the original version is maintained in a cache. You can view
each version using row["col", DataRowVersion.Current] or row["col", DataRowVersion.Original].
You can add your own custom property information to a dataset using the ExtendedProperties property.
This returns a PropertyCollection object,
so you can read and write properties as follows:
ds.ExtendedProperties.Add("LastUpdated", "Value1");
Console.WriteLine(ds.ExtendedProperties["LastUpdated"]);
You can filter a table with a SQL
WHERE clause. Simply add it to the table with similar syntax to the following:
foreach (DataRow row in tbl.Select("Country='UK' AND City =
'Nottingham'"))
Console.WriteLine(row["CompanyName"]);
The DataTable.Select() method
contains an overload to support sort orders also:
tbl.Select("CompanyName LIKE 'Micro%'", "Country DESC")
You can create a DataView object
using similar syntax; this can be bound to a Windows or web form control:
vue = new DataView(tbl, criteria, sortOrder, rowState);
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