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主题： [转帖]Android入门开发之在SQLite中使用事务

周逸涵

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发表于：

2013-7-9 10:16:53 | [全部帖] [楼主帖]

楼主

^{银行转账
1)update person set amount=amount-10 where personid=1;
2)update person set amount=amount+10 where personid=2;
以上个例子为基础，修改DBOpenHelper类，增加amount字段升级数据库
[java]view plaincopy
package cn.leigo.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {

       public DBOpenHelper(Context context) {
             super(context, "leigo.db", null, 3); //<包>/databases/
       }

       @Override
       public void onCreate(SQLiteDatabase db) {// 数据库第一次被创建的时候调用的
             db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20))");
       }

       @Override
       public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
             db.execSQL("ALTER TABLE person ADD amount integer");
       }

}

在Person类中增加amount变量:
[java]view plaincopy
package cn.leigo.domain;
public class Person {
       private Integer id;
       private String name;
       private String phone;
       private Integer amount;

       public Person() {
       }

       public Person(String name, String phone, Integer amount) {
             this.name = name;
             this.phone = phone;
             this.amount = amount;
       }

       public Person(Integer id, String name, String phone, Integer amount) {
             this.id = id;
             this.name = name;
             this.phone = phone;
             this.amount = amount;
       }

       public Integer getId() {
             return id;
       }

       public void setId(Integer id) {
             this.id = id;
       }

       public String getName() {
             return name;
       }

       public void setName(String name) {
             this.name = name;
       }

       public String getPhone() {
             return phone;
       }

       public void setPhone(String phone) {
             this.phone = phone;
       }

       public Integer getAmount() {
             return amount;
       }

       public void setAmount(Integer amount) {
             this.amount = amount;
       }

       @Override
       public String toString() {
             return "Person [id=" + id + ", name=" + name + ", phone=" + phone
             + ", amount=" + amount + "]";
       }

}

修改报错的类
更新数据
[java]view plaincopy
public void testUpdateAmount() throws Exception {
       PersonService service = new PersonService(getContext());
       Person person1 = service.find(1);
       Person person2 = service.find(2);
       person1.setAmount(100);
       person2.setAmount(50);
       service.update(person1);
       service.update(person2);
}

[java]view plaincopy
public void payment() {
       SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
       // 开启事务
       db.beginTransaction();
       db.execSQL("UPDATE person SET amount=amount-10 where personid=1");
       //System.out.println(1/0);
       db.execSQL("UPDATE person SET amount=amount+10 where personid=2");
       db.setTransactionSuccessful();
       // 结束事务，有两种情况:commit、rollback
       // 事务的提交或者回滚是由事务的标识决定的，如果事务的标识为true,事务就会提交否则回滚，默认情况下事务的标识为false
       db.endTransaction();
       db.close();

}
[java]view plaincopy
public void testPayment() throws Exception {
       PersonService service = new PersonService(getContext());
       service.payment();
}

将
[java]view plain}

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