标签：
啦啦啦啦啦啦啦 写这个不用多长时间,我直接写代码注释都是些语句,Sql语句和Api来操作数据库 ,语句的参数我会注释
SQLite数据库
创建数据库需要使用的api：SQLiteOpenHelper
必须定义一个构造方法：
//arg1:数据库文件的名字 //arg2:游标工厂 //arg3:数据库版本 public MyOpenHelper(Context context, String name, CursorFactory factory, int version){ }
//数据库被创建时会调用：onCreate方法
//数据库升级时会调用：onUpgrade方法
2创建数据库:
//创建OpenHelper对象 MyOpenHelper oh = new MyOpenHelper(getContext(), "person.db", null, 1); //获得数据库对象,如果数据库不存在，先创建数据库，后获得，如果存在，则直接获得 SQLiteDatabase db = oh.getWritableDatabase(); * getWritableDatabase()：打开可读写的数据库 * getReadableDatabase()：在磁盘空间不足时打开只读数据库，否则打开可读写数据库 * 在创建数据库时创建表 public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("create table person (_id integer primary key autoincrement, name char(10), phone char(20), money integer(20))"); }
数据库的增删改查
一些简单的SQL语句:
insert into person (name, phone, money) values (‘张三‘, ‘159874611‘, 2000); delete from person where name = ‘李四‘ and _id = 4; update person set money = 6000 where name = ‘李四‘; select name, phone from person where name = ‘张三‘;
执行SQL语句实现增删改查
//插入 db.execSQL("insert into person (name, phone, money) values (?, ?, ?);", new Object[]{"张三", 15987461, 75000}); //查找 Cursor cs = db.rawQuery("select _id, name, money from person where name = ?;", new String[]{"张三"}); //测试方法执行前会调用此方法 protected void setUp() throws Exception { super.setUp(); // 获取虚拟上下文对象 oh = new MyOpenHelper(getContext(), "people.db", null, 1); }
###使用api实现增删改查
//插入 //以键值对的形式保存要存入数据库的数据 ContentValues cv = new ContentValues(); cv.put("name", "刘能"); cv.put("phone", 1651646); cv.put("money", 3500); //返回值是改行的主键，如果出错返回-1 long i = db.insert("person", null, cv); // 删除 //返回值是删除的行数 int i = db.delete("person", "_id = ? and name = ?", new String[]{"1", "张三"}); * 修改 ContentValues cv = new ContentValues(); cv.put("money", 25000); int i = db.update("person", cv, "name = ?", new String[]{"赵四"}); // 查询 //arg1:要查询的字段 //arg2：查询条件 //arg3:填充查询条件的占位符 Cursor cs = db.query("person", new String[]{"name", "money"}, "name = ?", new String[]{"张三"}, null, null, null); while(cs.moveToNext()){ // 获取指定列的索引值 String name = cs.getString(cs.getColumnIndex("name")); String money = cs.getString(cs.getColumnIndex("money")); System.out.println(name + ";" + money); }
事务:
什么是事务
保证多条SQL语句要么同时成功，要么同时失败
最常见案例：银行转账
事务api
try { //开启事务 db.beginTransaction(); ........... //设置事务执行成功 db.setTransactionSuccessful(); } finally{ //关闭事务 //如果此时已经设置事务执行成功，则sql语句生效，否则不生效 db.endTransaction(); }
先创建类MyOpenHelper 继承自SQLiteOpenHelper
public class MyOpenHelper extends SQLiteOpenHelper { public MyOpenHelper(Context context) { //1:数据库文件名字 //2：游标工厂，游标等同于结果集，传null使用默认工厂 //3：版本，不能小于1，用于升级 super(context, "people.db", null, 1); } //创建数据库时调用 @Override public void onCreate(SQLiteDatabase db) { //创建表 db.execSQL("create table person(_id integer primary key autoincrement, name char(10), phone char(20), salary integer(10))"); } //升级数据库时调用 @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { System.out.println("数据库升级"); } }
XML文件 :新建测试类 并制定指令集 包,类库
<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17" /> <instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="com.ace.sqlite"> </instrumentation> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <uses-library android:name="android.test.runner"/>
public class Test extends AndroidTestCase{ private MyOpenHelper oh; private SQLiteDatabase db; public void test(){ // 获取虚拟上下文 MyOpenHelper oh = new MyOpenHelper(getContext()); //如果数据库不存在，先创建，再打开，如果存在，就直接打开 SQLiteDatabase db = oh.getWritableDatabase(); } //测试方法执行前调用 @Override protected void setUp() throws Exception { super.setUp(); oh = new MyOpenHelper(getContext()); db = oh.getWritableDatabase(); } @Override protected void tearDown() throws Exception { super.tearDown(); db.close(); } public void insert(){ // db.execSQL("insert into person(name, phone, salary) values (?, ?, ?)", new Object[]{"亚索", "13503723845", 5000}); db.execSQL("insert into person(name, phone, salary) values (?, ?, ?)", new Object[]{"德玛", "18543843843", 2000}); db.execSQL("insert into person(name, phone, salary) values (?, ?, ?)", new Object[]{"蒙多", "12345678912", 3000}); } public void delete(){ db.execSQL("delete from person where name = ?", new Object[]{"亚索"}); } public void update(){ db.execSQL("update person set salary = ? where name = ?", new Object[]{5200, "亚索"}); } public void select(){ Cursor cursor = db.rawQuery("select * from person", null); //把指针移动至下一行 while(cursor.moveToNext()){ //先通过列名，获取列索引，然后再获取该列的内容 String name = cursor.getString(cursor.getColumnIndex("name")); String phone = cursor.getString(cursor.getColumnIndex("phone")); int salary = cursor.getInt(cursor.getColumnIndex("salary")); System.out.println(name + ";" + phone + ";" + salary); } } public void insertApi(){ ContentValues values = new ContentValues(); values.put("name", "女枪"); values.put("phone", "1388888888"); values.put("salary", "8000"); //返回值-1，插入失败 long l = db.insert("person", null, values); System.out.println(l); } public void deleteApi(){ int i = db.delete("person", "_id = ?", new String[]{"6"}); System.out.println(i); } public void updateApi(){ ContentValues values = new ContentValues(); values.put("name", "德邦"); int i = db.update("person", values, "_id = ?", new String[]{"2"}); System.out.println(i); } public void selectApi(){ //arg1: 查询的字段 //arg2: 查询的where条件 //arg3: where条件的占位符 Cursor cursor = db.query("person", null, null, null, null, null, null, null); while(cursor.moveToNext()){ String name = cursor.getString(1); String phone = cursor.getString(2); int salary = cursor.getInt(3); System.out.println(name + ";" + phone + ";" + salary); } } public void transaction(){ try{ //开启事务 db.beginTransaction(); ContentValues values = new ContentValues(); values.put("salary", 4500); db.update("person", values, "name = ?", new String[]{"亚索"}); //清空values的内容 values.clear(); values.put("salary", 2500); db.update("person", values, "name = ?", new String[]{"的吗"}); // int i = 1 / 0; //这句是为了打断事务,让数据回滚 //设置事务执行成功，提交时如果这行代码没有执行过，就会回滚 db.setTransactionSuccessful(); } catch (Exception e) { e.printStackTrace(); } finally{ //关闭事务，提交数据 db.endTransaction(); } } }
转载的请注明出处 Acein20160131
啊啊啊啊啊啊啊今天就写,炒鸡简单 数据库Sqlite的创建,库的增删改查
标签：
原文地址：http://www.cnblogs.com/AceIsSunshineRain/p/5172893.html
