Mata kuliah : M0874 – Programming II
Tahun
: 2010
Database, SQL, and ADO .NET- Part 2
Session 12
Outline Materi
•Programming with ADO .NET: Extracting
Information from a Database
•Programming with ADO .NET: Modifying a
Database
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The SqlCommand Object
•A SqlCommand object allows you to specify what type of interaction you
want to perform with a database.
•For example, you can do select, insert, modify, and delete commands on
rows of data in a database table.
•Similar to other C# objects, you instantiate a SqlCommand object via the
new instance declaration, as follows:
SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);
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Querying Data
•Instantiate a new command with a query and
connection
SqlCommand cmd = new SqlCommand("select
CategoryName from Categories", conn);
•Call Execute reader to get query results
SqlDataReader rdr = cmd.ExecuteReader();
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Inserting Data
•Prepare command string
string insertString = @"
insert into Categories
(CategoryName, Description)
values ('Miscellaneous', 'Whatever doesn''t fit elsewhere')";
•Instantiate a new command with a query and
connection
SqlCommand cmd = new SqlCommand(insertString, conn);
•Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
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Updating Data
•Prepare command string
string updateString = @"
update Categories
set CategoryName = 'Other'
where CategoryName = 'Miscellaneous'";
•Instantiate a new command with command text only
SqlCommand cmd = new SqlCommand(updateString);
•Set the Connection property
cmd.Connection = conn;
•Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
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Deleting Data
•Prepare command string
string deleteString = @"
delete from Categories
where CategoryName = 'Other'";
•Instantiate a new command
SqlCommand cmd = new SqlCommand();
•Set the CommandText property
cmd.CommandText = deleteString;
•Set the Connection property
cmd.Connection = conn;
•Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
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Reading Data with the SqlDataReader
•SqlDataReader objects allow you to read data in a
fast forward-only manner.
•You obtain data by reading each row from the data
stream.
•Call the Close method of the SqlDataReader to
ensure there are not any resource leaks.
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Reading Data with the SqlDataReader
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Working with Disconnected Data –
The DataSet and SqlDataAdapter
•The SqlDataAdapter performs the following tasks
when filling a DataSet with data:
•Open connection
•Retrieve data into DataSet
•Close connection
•Performs the following actions when updating data
source with DataSet changes:
•Open connection
•Write changes from DataSet to data source
•Close connection
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References
•http://www.csharpstation.com/Tutorials/AdoDotNet/Lesson01.aspx
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