一、SQLite介绍

SQLite是一个小型的内嵌于Android的数据库；我们不需要引入驱动即可访问它；

SQLite可视化工具：SQLite Expert Professional 3；

二、Android访问SQLite

主要步骤：

(1)创建某个类继承SQLiteOpenHelper,并重写
-- 带Context参数的构造函数; //用来创建数据库 -- onCreate(SQLiteDatabase db); //在创建数据库时调用 -- onUpgrade(SQLiteDatabase db,int old,int newversion); //数据库版本更改时调用
(2)创建数据库：SQLiteDatabase db = helper.getWritableDatabase();
(3)SQL语句：db.execSQL(String sql);

具体模板代码如下：

package org.xiazdong.db.util;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;public class DatabaseHelper extends SQLiteOpenHelper{private static final String TAG = "DatabaseHelper";private static  int VERSION = 1;public DatabaseHelper(Context context) {super(context, "test.db", null, VERSION);}@Overridepublic void onCreate(SQLiteDatabase db) {db.execSQL("create table 语句");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {Log.i(TAG, "版本更新...");}}

当创建数据库时，database存放在/data/data/package/databases 目录中；

1.打开数据库

SQLiteDatabase db = helper.getWritableDatabase(); SQLiteDatabase db = helper.getReadableDatabase(); //此函数内部其实也调用了getWritableDatabase()函数，即调用了此函数，也可以写数据

2.insert语句

(1)db.execSQL("insert into person(name,age) values(?,?)",new Object[]{"xiazdong",20}); (2)

ContentValues values = new ContentValues();values.put("name","xiazdong");values.put("age",20);db.insert("tablename",null,values);

3.delete语句

(1)db.execSQL("delete from person where id=?",new Object[]{id}); (2)db.delete("tablename","id=?",new String[]{id+""});

4.update语句

(1)

db.exeSQL("update person set age=? where name=?",new Object[]{30,"xiazdong"});

(2)

ContentValues values = new ContentValues();values.put("age",30);/*set子句*/db.update("tablename",values,"name=?"/*where子句*/,new String[]{"xiazdong"}/*where子句参数*/);

5.query语句

(1)

Cursor cursor = db.rawQuery("select * from person where name=?",new Object[]{"xiazdong"});while(cursor.moveToNext()){    //int index = cursor.getColumnIndex(String name);//根据name获得索引    //String name = cursor.getString(int index);    //根据索引获得值    String name = cursor.getString(cursor.getColumnIndex("name")); }

(2) Cursor cursor = db.query("tablename",null /*表示select * */,"name=?" /*where语句*/,new String[]{"xiazdong"},null /*group by 语句*/,null /*having 语句*/,null /*order by语句*/,null /*limit 语句*/);

6.分页语句

Cursor cursor = db.rawQuery("select * from person limit ?,?",new Object[]{5,5}); //第一个5表示跳过5条记录，下一个5为查询结果的记录个数 while(cursor.moveToNext()){ String name = cursor.getString(cursor.getColumnIndex("name")); }

7.获得记录个数语句

(1)

Cursor cursor = db.rawQuery("select count(*) from person", null);cursor.moveToFirst();int count = cursor.getInt(0);

(2) db.query("person",new String[]{"count(*)"},null,null,null,null,null,null);

三、事务操作

模板代码如下：

db.beginTransaction();try{//事务操作db.setTransactionSuccessful();//此句必须要有，不然db.endTransaction()默认为回滚}finally{db.endTransaction();}

Android入门：SQLite