在C#中实现3层架构(4)
public DACustomer(BOCustomer cus)
{
// A reference of the business object class
}
//standard dataset function that adds a new customer
public void Add(BOCustomer cus)
{
String str = BuildAddString(cus);
OpenCnn();
//Open command option - cnn parameter is imporant
OleDbCommand cmd = new OleDbCommand(str,cnn);
//execute connection
cmd.ExecuteNonQuery();
// close connection
CloseCnn();
}
//standard dataset function that updates
//details of a customer based on ID
public void Update(BOCustomer cus)
{
OpenCnn();
String selectStr = "UPDATE " + thisTable +
" set " + cus_LName + " = '" + cus.LName + "'" +
", " + cus_FName + " = '" + cus.FName + "'" +
", " + cus_Address + " = '" + cus.Address + "'" +
", " + cus_Tel + " = '" + cus.Tel + "'" +
" where cus_ID = '" + cus.cusID + "'";
OleDbCommand cmd = new OleDbCommand(selectStr,cnn);
cmd.ExecuteNonQuery();
CloseCnn();
}
//standard dataset function that finds and
//return the detail of a customer in a dataset
public DataSet Find(String argStr)
{
DataSet ds=null;
try
{
OpenCnn();
String selectStr = "select * from " + thisTable +
" where cus_ID = '" + argStr + "'";
OleDbDataAdapter da =
new OleDbDataAdapter(selectStr,cnn);
ds = new DataSet();
da.Fill(ds,thisTable);
CloseCnn();
}
catch(Exception e)
{
String Str = e.Message;
}
return ds;
}
private void OpenCnn()
{
// initialise connection
String cnnStr = CnnStr;
cnn = new OleDbConnection(cnnStr);
// open connection
cnn.Open();
}
private void CloseCnn()
{
// 5- step five
cnn.Close();
}
// just a supporting function that builds
// and return the insert string for dataset.
private String BuildAddString(BOCustomer cus)
{
// these are the constants as
// set in the top of this module.
strTable="Insert into " + thisTable;
strFields=" (" + cus_ID +
"," + cus_LName +
"," + cus_FName +
"," + cus_Address +
"," + cus_Tel + ")";
//these are the attributes of the
//customer business object.
strValues= " Values ( '" + cus.cusID +
"' , '" + cus.LName +
"' , '" + cus.FName +
"' , '" + cus.Address +
"' , '" + cus.Tel + "' )";
insertStr = strTable + strFields + strValues;
return insertStr;
}
}
}