Android之采用execSQL与rawQuery方法完成数据的添删改查操作详解

package com.zyq.service; 
import java.util.ArrayList; 
import java.util.List; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import com.zyq.voo.Person; 
public class PersonService 
{ 
private DBOpenHelper helper; 
public PersonService(Context context) 
{ 
helper=new DBOpenHelper(context); 
} 
/**
 * 新增一条记录
 * @param person
 */ 
public void save(Person person) 
{ 
SQLiteDatabase db=helper.getWritableDatabase();//Create and/or open a database that will be used for reading and writing 
db.execSQL("INSERT INTO person(name,phone) values(?,?)",new Object[]{person.getName().trim(),person.getPhone().trim()});//使用占位符进行转译 
//  db.close();  不关数据库连接 。可以提高性能 因为创建数据库的时候的操作模式是私有的。 
//代表此数据库，只能被本应用所访问 单用户的，可以维持长久的链接 
}  
/**
 * 更新某一条记录
 * @param person
 */ 
public void update(Person person) 
{ 
SQLiteDatabase db=helper.getWritableDatabase(); 
db.execSQL("update person set phone=?,name=? where personid=?", 
new Object[]{person.getPhone().trim(),person.getName().trim(),person.getId()}); 
} 
/**
 * 根据ID查询某条记录
 * @param id
 * @return
 */ 
public Person find(Integer id) 
{ 
SQLiteDatabase db=helper.getReadableDatabase(); 
Cursor cursor=db.rawQuery("select * from person where personid=?", new String[]{id.toString()});//Cursor 游标和 ResultSet 很像 
if(cursor.moveToFirst())//Move the cursor to the first row. This method will return false if the cursor is empty. 
{ 
int personid=cursor.getInt(cursor.getColumnIndex("personid")); 
String name=cursor.getString(cursor.getColumnIndex("name")); 
String phone=cursor.getString(cursor.getColumnIndex("phone")); 

return new Person(personid,name,phone); 
} 
return null; 
} 
/**
 * 删除某一条记录
 * @param id
 */ 
public void delete(Integer id) 
{ 
SQLiteDatabase db=helper.getWritableDatabase(); 
db.execSQL("delete from person where personid=?", 
new Object[]{id}); 
} 

/**
 * 得到记录数
 * @return
 */ 
public long getCount() 
{ 
SQLiteDatabase db=helper.getReadableDatabase(); 
Cursor cursor=db.rawQuery("select count(*) from person", null); 
cursor.moveToFirst(); 
return cursor.getLong(0); 
} 
/**
 * 分页查询方法 SQL语句跟MySQL的语法一样
 * @return
 */ 
public List<Person> getScrollData(int offset,int maxResult) 
{ 
List<Person> persons=new ArrayList<Person>(); 
SQLiteDatabase db=helper.getReadableDatabase(); 
Cursor cursor=db.rawQuery("select * from person limit ?,?",  
new String[]{String.valueOf(offset),String.valueOf(maxResult)}); 
while (cursor.moveToNext()) 
{ 
int personid=cursor.getInt(cursor.getColumnIndex("personid")); 
String name=cursor.getString(cursor.getColumnIndex("name")); 
String phone=cursor.getString(cursor.getColumnIndex("phone")); 

persons.add(new Person(personid,name,phone)); 
} 

return persons; 
} 
}