对android内置的sqlLite数据库进行增、删、改、查操作
1.创建数据库
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
public DBOpenHelper(Context context) {
// 第一个参数表示context对象，第二个参数表示数据库的名称，第三个数表示游标对象，可以传入NULL，第四个参数表示数据库的版本号
super(context, "kafei.db", null, 2);
}
/**
* onCreate方法是在数据库第一次被创建的时候调用
*/
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table user(id integer primary key autoincrement,name varchar(20))");
}
/**
* 在数据库版本号发生改变的时候调用
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("alter table user add age integer");// 为user表增加一列
}
}DBOpenHelper dbOpenHelper = new DBOpenHelper(getContext());
dbOpenHelper.getWritableDatabase();// 调用getWritableDatabase()方法就会自动创建数据库
2.利用SQLiteDatabase的execSQL方法手动编写SQL语句对数据库进行增删改查操作：
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import cn.kafei.pojo.User;
public class UserService {
private DBOpenHelper dbOpenHelper;
public UserService(Context context) {
this.dbOpenHelper = new DBOpenHelper(context);
}
/**
* 添加记录
*
* @param user
*/
public void save(User user) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("insert into user(name,age)values(?,?)",
new Object[] { user.getName(), user.getAge() });
}
/**
* 删除记录
*
* @param id
* 记录ID
*/
public void delete(Integer id) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("delete from user where id=?", new Object[] { id });
}
/**
* 更新记录
*
* @param user
*/
public void update(User user) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("update user set name=?,age=? where id=?", new Object[] {
user.getName(), user.getAge(), user.getId() });
}
/**
* 查找记录
*
* @param id
* 记录ID
*/
public User find(Integer id) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from user where id=?",
new String[] { id.toString() });
if (cursor.moveToFirst()) {
int userid = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
return new User(userid, name, age);
}
cursor.close();
return null;
}
/**
* 分页获取记录
*
* @param offset
* 跳过前面多少条记录
* @param maxResult
* 每页获取多少条记录
* @return
*/
public List getScrollData(int offset, int maxResult) {
List users = new ArrayList();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery(
"select * from user order by id asc limit ?,?", new String[] {
String.valueOf(offset), String.valueOf(maxResult) });
while (cursor.moveToNext()) {
int userid = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
users.add(new User(userid, name, age));
}
cursor.close();
return users;
}
/**
* 获取记录总数
*
* @return
*/
public long getCount() {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(*) from user", null);
cursor.moveToFirst();
long result = cursor.getLong(0);
cursor.close();
return result;
}
} import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import cn.kafei.pojo.User;
public class OtherService {
private DBOpenHelper dbOpenHelper;
public OtherService(Context context) {
this.dbOpenHelper = new DBOpenHelper(context);
}
/**
* 添加记录
*
* @param user
*/
public void save(User user) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", user.getName());
values.put("age", user.getAge());
// 第一个参数表的名称,
// 第二个参数:空置字段，假如指定name为空值字段,则组拼的SQL语句为insert into user(name)
// values(null),最终目的是为了保证SQL语句的正常执行
// 在第三个参数为null或者为空集合的时候使用
// 第三个参数:表示要添加的值，
db.insert("user", null, values);
// db.execSQL("insert into user(name,age)values(?,?)",new
// Object[]{user.getName(),user.getAge()});
}
/**
* 删除记录
*
* @param id
* 记录ID
*/
public void delete(Integer id) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.delete("user", "id=?", new String[] { id.toString() });
// db.execSQL("delete from user where id=?",new Object[]{id});
}
/**
* 更新记录
*
* @param user
*/
public void update(User user) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", user.getName());
values.put("age", user.getAge());
// 第二个参数表示要更新的值
db.update("user", values, "id=?", new String[] { user.getId()
.toString() });
// db.execSQL("update user set name=?,age=? where id=?",new
// Object[]{user.getName(),user.getAge(),user.getId()});
}
/**
* 查找记录
*
* @param id
* 记录ID
*/
public User find(Integer id) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
/**
* 第一个参数：要查询的表 第二个参数：要查询的列,如果要查询所有的列，就传入Null 第三个参数:查询条件 第四个参数：查询条件的值
* 第五个参数：分组条件 第六个参数：having 第七个参数：排序
*/
Cursor cursor = db.query("user", new String[] { "id", "name", "age" },
"id=?", new String[] { id.toString() }, null, null, null);
// Cursor cursor=db.rawQuery("select * from user where id=?", new
// String[]{id.toString()});
if (cursor.moveToFirst()) {
int userid = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
return new User(userid, name, age);
}
cursor.close();
return null;
}
/**
* 分页获取记录
*
* @param offset
* 跳过前面多少条记录
* @param maxResult
* 每页获取多少条记录
* @return
*/
public List getScrollData(int offset, int maxResult) {
List users = new ArrayList();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.query("user", null, null, null, null, null,
"id asc", offset + "," + maxResult);
// Cursor
// cursor=db.rawQuery("select * from user order by id asc limit ?,?",
// new String[]{String.valueOf(offset),String.valueOf(maxResult)});
while (cursor.moveToNext()) {
int userid = cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
users.add(new User(userid, name, age));
}
cursor.close();
return users;
}
/**
* 获取记录总数
*
* @return
*/
public long getCount() {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.query("user", new String[] { "count(*)" }, null,
null, null, null, null);
// Cursor cursor=db.rawQuery("select count(*) from user", null);
cursor.moveToFirst();
long result = cursor.getLong(0);
cursor.close();
return result;
}
} import java.util.List;
import cn.kafei.pojo.User;
import cn.kafei.service.DBOpenHelper;
import cn.kafei.service.OtherService;
import android.test.AndroidTestCase;
import android.util.Log;
public class OtherServiceTest extends AndroidTestCase {
private static final String TAG="UserServiceTest";
public void testCreateDB() throws Exception {
DBOpenHelper dbOpenHelper = new DBOpenHelper(getContext());
dbOpenHelper.getWritableDatabase();// 调用getWritableDatabase()方法就会自动创建数据库
}
public void testSave() throws Exception {
OtherService service=new OtherService(getContext());
// for (int i = 0; i <20; i++) {
service.save(new User("lht", 28));
// }
}
public void testDelete() throws Exception {
OtherService service=new OtherService(getContext());
service.delete(1);
}
public void testUpdate() throws Exception {
OtherService service=new OtherService(getContext());
User user=new User();
user.setAge(100);
user.setId(21);
service.update(user);
}
public void testFind() throws Exception {
OtherService service=new OtherService(getContext());
User user=service.find(1);
Log.i(TAG,user.toString());
}
public void testScrollData() throws Exception {
OtherService service=new OtherService(getContext());
//第一个参数表示页数，第二个参数表示每页显示的记录数
List users=service.getScrollData(5, 5);
for (User user : users) {
Log.i(TAG,user.toString());
}
}
public void testCount() throws Exception {
OtherService service=new OtherService(getContext());
Log.i(TAG, String.valueOf(service.getCount()));
}
} public void updateMoney(){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
db.beginTransaction();//开启事务
try{
db.execSQL("update user set amount=amount-10 where id=21");
db.execSQL("update user set amount=amount+10 where id=22");
db.setTransactionSuccessful();//设置事务的标志为true
}finally{
//结束事务,有两种情况，一种是commit,一种是rollback,事务的提交或回滚是由事务的标志决定的,默认情况下，事务的标志为false，如果事务的标志为true则会提交否则就会回滚
db.endTransaction();
}
}