// prepare command string
string deleteString = @"
delete from Categories
where CategoryName = ''''Other''''";
// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand();
// 2. Set the CommandText property
cmd.CommandText = deleteString;
// 3. Set the Connection property
cmd.Connection = conn;
// 4. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}
/// <summary>
/// use ExecuteScalar method
/// </summary>
/// <returns>number of records</returns>
public int GetNumberOfRecords()
{
int count = -1;
try
{
// Open the connection
conn.Open();
// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand("select count(*) from Categories", conn);
// 2. Call ExecuteNonQuery to send command
count = (int)cmd.ExecuteScalar();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
return count;
}
}
In Listing 1, the SqlConnection object is instantiated in the SqlCommandDemo structure. This is okay because the object itself will be cleaned up when the CLR garbage collector executes. What is important is that we close the connection when we are done using it. This program opens the connection in a try block and closes it in a finally block in each method.
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