␡
- What Is a Database?
- Getting Data Out of Databases
- Kinds of Databases
- ODBC
- Database Structure
- Using ADO.NET
- Adding Rows to Database Tables Using ADO.NET
- Building the Façade Classes
- Making the ADO.NET Façade
- Creating Classes for Each Table
- Building the Price Table
- Loading the Database Tables
- The Final Application
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Loading the Database Tables
With all these classes derived, we can write a class to load the table from the data file. It reads the file once and builds the Store and Food database tables. Then it reads the file again and looks up the store and food keys and adds them to the array list in the Price class. Finally, it creates the Price table.
public class DataLoader {
private csFile vfile;
private Stores store;
private Foods fods;
private Prices price;
private DBase db;
//-----
public DataLoader(DBase datab) {
db = datab;
store = new Stores(db);
fods = new Foods (db);
price = new Prices(db);
}
//-----
public void load(string dataFile) {
string sline;
int storekey, foodkey;
StringTokenizer tok;
//delete current table contents
store.delete();
fods.delete();
price.delete();
//now read in new ones
vfile = new csFile(dataFile);
vfile.OpenForRead();
sline = vfile.readLine();
while (sline != null){
tok = new StringTokenizer(sline, ",");
store.addTableValue(tok.nextToken()); //store
fods.addTableValue(tok.nextToken()); //food
sline = vfile.readLine();
}
vfile.close();
//construct store and food tables
store.makeTable();
fods.makeTable();
vfile.OpenForRead();
sline = vfile.readLine();
while (sline != null) {
//get the gets and add to storefoodprice objects
tok = new StringTokenizer(sline, ",");
storekey = store.getKey(tok.nextToken(), "Storekey");
foodkey = fods.getKey(tok.nextToken(), "Foodkey");
price.addRow(storekey, foodkey,
Convert.ToSingle (tok.neXtToken()));
sline = vfile.readLine();
}
//add all to price table
price.makeTable();
vfile.close();
}
}