布局文件
创建了四个按键，分别对应增删改查
数据库操作
package xidian.dy.com.chujia;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.Toast;public class MainActivity extends AppCompatActivity implements View.OnClickListener { private SQLiteDatabase db; private MainActivity mContext; private int i = 1; @Override protected void onCreate(Bundle savedInstanceState) { mContext = MainActivity.this; super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); MyDBOpenHelper myDBHelper = new MyDBOpenHelper(mContext, "my.db", null, 1); db = myDBHelper.getWritableDatabase(); bindViews(); } private void bindViews() { Button btn_insert = (Button) findViewById(R.id.btn_insert); Button btn_query = (Button) findViewById(R.id.btn_query); Button btn_update = (Button) findViewById(R.id.btn_update); Button btn_delete = (Button) findViewById(R.id.btn_delete); if(btn_query != null) btn_query.setOnClickListener(this); if(btn_insert != null) btn_insert.setOnClickListener(this); if(btn_update != null) btn_update.setOnClickListener(this); if(btn_delete != null) btn_delete.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.btn_insert: ContentValues values1 = new ContentValues(); //name为数据库中属性名,第二个为欲插入的值 values1.put("name", "呵呵~" + i); i++; //参数依次是：表名，强行插入null值得数据列的列名，一行记录的数据 db.insert("person", null, values1); Toast.makeText(mContext, "插入完毕~", Toast.LENGTH_SHORT).show(); break; case R.id.btn_query: StringBuilder sb = new StringBuilder(); //参数依次是:表名，列名，where约束条件，where中占位符提供具体的值，指定group by的列，进一步约束 //指定查询结果的排序方式 Cursor cursor = db.query("person", null, null, null, null, null, null); if (cursor.moveToFirst()) { do { int id = cursor.getInt(cursor.getColumnIndex("_id")); String name = cursor.getString(cursor.getColumnIndex("name")); sb.append("id：" + id + "：" + name + "\n"); } while (cursor.moveToNext()); } cursor.close(); Toast.makeText(mContext, sb.toString(), Toast.LENGTH_SHORT).show(); break; case R.id.btn_update: ContentValues values2 = new ContentValues(); values2.put("name", "嘻嘻~"); //参数依次是表名，修改后的值，where条件，以及约束，如果不指定三四两个参数，会更改所有行 db.update("person", values2, "name = ?", new String[]{"呵呵~2"}); break; case R.id.btn_delete: //参数依次是表名,where条件,约束 db.delete("person", "_id = ?", new String[]{"3"}); //多个条件// db.delete("person", "_id=? and name=?", new String[]{"1", "小名"}); break; } }} 这里先创建一个数据库助手，通过该助手获取数据库操作对象。利用该对象提供的API来操作数据库。
数据库助手类
package xidian.dy.com.chujia;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;/** * Created by dy on 2016/6/13. */public class MyDBOpenHelper extends SQLiteOpenHelper { public MyDBOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) { super(context, "my.db", null, 1); } @Override //数据库第一次创建时被调用 public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE person(_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20))"); } //软件版本号发生改变时调用 @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL"); }} 事务
如果在数据库操作中使用到了事务可以参考以下的代码
//转账事物 public void transaction(){ try { db.beginTransaction(); ContentValues values = new ContentValues(); values.put("salary", 9000); db.update("person",values,"name=?", new String[]{"小王"}); values.clear(); values.put("salary", 11000); db.update("person", values, "name=?", new String[]{"小张"}); //设置事务执行成功 db.setTransactionSuccessful(); }finally { //关闭事物,同时提交,如果已经设置事务执行成功,那么sql将会生效,否则SQL回滚 db.endTransaction(); } }