这个using是什么意思,和using System; 的using是一样的吗?
public CustomerData GetCustomerByEmail(String emailAddress, byte [] password)
{
//
// Check preconditions
//
ApplicationAssert.CheckCondition(emailAddress != String.Empty, "Email address is required", ApplicationAssert.LineNumber);
ApplicationAssert.CheckCondition(password.Length != 0, "Password is required", ApplicationAssert.LineNumber);
//
// Get the customer dataSet
//
CustomerData dataSet;
using (DataAccess.Customers customersDataAccess = new DataAccess.Customers())
{
dataSet = customersDataAccess.LoadCustomerByEmail(emailAddress);
}
//
// Verify the customer's password
//
DataRowCollection rows = dataSet.Tables[CustomerData.CUSTOMERS_TABLE].Rows;
if ( ( rows.Count == 1 ))
{
byte [] dbPassword = (byte[])rows[0][CustomerData.PASSWORD_FIELD];
if (ComparePasswords (dbPassword, password))
return dataSet;
else
return null;
}
else
return null;
}