本篇整合Android使用数据库，要保存一个实体类的样本。
首先看一下数据库语句：
ORM:关系对象映射
添加数据：
ContentValues values = new ContentValues();
values.put("name", "小丽");
values.put("phone", "110");
mDB.insert("student",//表名
null, //规避插入语句的错误
values );//插入的值 删除数据：
mDB.delete("student", //表名
"name =?",//条件语句
new String[]{"小丽"});//条件语句的占位符改动数据：
ContentValues values = new ContentValues();
values.put("phone", "10086");
mDB.update("student",//表名
values, //要改动的值
"name =?",//条件语句
new String[]{"小丽"});查询数据：
Cursor cursor = mDB.query("student",//表名
null,//查询的字段
null,//条件语句
null,//条件语句的占位符
null,//分组语句
null,//分组条件
null);//排序
boolean toFirst = cursor.moveToFirst();
while(toFirst){
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
MyData myData = new MyData(name, phone);
dataList.add(myData);
toFirst = cursor.moveToNext();
} 以下是数据库创建及使用步骤
1、方法调用
private DBMang_Order dbMang_Order; dbMang_Order=DBMang_Order.getInstance(getApplicationContext());
//查询
ArrayList<OrderUncheck> uncheckList = dbMang_Order.query();
//删除
dbMang_Order.delete(orderNo);
//添加
dbMang_Order.insert(new OrderUncheck(orderNo, account, action));
//改动
dbMang_Order.update(new OrderUncheck(orderNo, account, action));
2、首先创建要存储的实体类
public class OrderUncheck {
String orderNo;
double account;
int action;
public String getOrderNo() {
return orderNo;
}
public void setOrderNo(String orderNo) {
this.orderNo = orderNo;
}
public double getAccount() {
return account;
}
public void setAccount(double account) {
this.account = account;
}
public int getAction() {
return action;
}
public void setAction(int action) {
this.action = action;
}
public OrderUncheck(String orderNo, double account, int action) {
super();
this.orderNo = orderNo;
this.account = account;
this.action = action;
}
}
3、创建数据库
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MySQL_Order extends SQLiteOpenHelper {
private static final String name = "count"; //数据库名称
private static final int version = 1; //数据库版本号
//第三个參数CursorFactory指定在运行查询时获得一个游标实例的工厂类,设置为null,代表使用系统默认的工厂类
public MySQL_Order(Context context) {
super(context, name, null, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql="CREATE TABLE neworder (_id INTEGER PRIMARY KEY AUTOINCREMENT,orderNo VARCHAR(200),account VARCHAR(19100),action VARCHAR(200))";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
4、代码中被调用的方法在这个类：增删改查
public class DBMang_Order {
private static DBMang_Order mDbManager=new DBMang_Order();
private static SQLiteDatabase mDb;
private static Context context;
private DBMang_Order() {
}
public static synchronized DBMang_Order getInstance(Context context){
DBMang_Order.context = context;
if(mDb==null){
MySQL_Order mySQL = new MySQL_Order(context);
mDb = mySQL.getWritableDatabase();
}
return mDbManager;
}
interface NewTable{
String TABLE_NAME="neworder";
String TABLE_COLUMN_orderNo="orderNo";
String TABLE_COLUMN_account="account";
String TABLE_COLUMN_action="action";
}
//增
public void insert(OrderUncheck info){
ContentValues values=new ContentValues();
values.put(NewTable.TABLE_COLUMN_orderNo, info.getOrderNo());
values.put(NewTable.TABLE_COLUMN_account, info.getAccount());
values.put(NewTable.TABLE_COLUMN_action, info.getAction());
Log.w("mDb.insert", ""+info);
Log.w("mDb.insert",""+ values);
mDb.insert(NewTable.TABLE_NAME, null, values);
}
//删
public void delete(String orderNo) {
Log.w("delete", orderNo);
mDb.delete(NewTable.TABLE_NAME, NewTable.TABLE_COLUMN_orderNo+"=?", new String[]{orderNo});
}
//改
public void update(OrderUncheck info){
ContentValues values = new ContentValues();
values.put(NewTable.TABLE_COLUMN_account, info.getAccount());
mDb.update(NewTable.TABLE_NAME, values, NewTable.TABLE_COLUMN_orderNo+"=? and "+NewTable.TABLE_COLUMN_orderNo+"=?
", new String[]{String.valueOf(info.getOrderNo()),""+info.getAccount()});
}
//查
public ArrayList<OrderUncheck> query(){
Cursor cursor = mDb.query(NewTable.TABLE_NAME, null, null, null, null, null, null);
ArrayList<OrderUncheck> list=new ArrayList<OrderUncheck>();
boolean toFirst = cursor.moveToFirst();
while (toFirst) {
String orderNo = cursor.getString(cursor.getColumnIndex(NewTable.TABLE_COLUMN_orderNo));
String account = cursor.getString(cursor.getColumnIndex(NewTable.TABLE_COLUMN_account));
String action = cursor.getString(cursor.getColumnIndex(NewTable.TABLE_COLUMN_account));
double accountd = Double.parseDouble(account);
int actiond=Integer.parseInt(action);
OrderUncheck order = new OrderUncheck(orderNo, accountd,actiond);
list.add(order);
toFirst=cursor.moveToNext();
}
cursor.close();
return list;
}
}
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