Android 学习 数据库表增加 删除 修改 查询

核心提示：//执行创建数据库SQL语句db.execSQL(DATABASE_CREATE);}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//判断数据库是否存在db.execSQL("DROP T

//执行创建数据库SQL语句

db.execSQL(DATABASE_CREATE);

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

//判断数据库是否存在

db.execSQL("DROP TABLE IF EXISTS diary");

onCreate(db);

}

}

package us.imnet.iceskysl.db.notepad;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

import android.database.sqlite.SQLiteDatabase.CursorFactory;

/**

* 创建数据库对象

* @author xuzhenqin

*

*/

public class DatabaseHelper extends SQLiteOpenHelper {

//数据库名称

private final static String DATABASE_NAME = "notepad";

//数据库版本号

private final static int DATABASE_VERSION = 1;

public static final String DATABASE_TABLE = "diary";

//数据表创建SQL语句

private static final String DATABASE_CREATE = "create table "+DATABASE_TABLE+" (_id integer primary key autoincrement, "

+ "title text not null, body text not null, created text not null);";

public DatabaseHelper(Context context) {

//调用父类构造方法创建数据库

super(context, DATABASE_NAME, null, DATABASE_VERSION);

}

@Override

public void onCreate(SQLiteDatabase db) {

//执行创建数据库SQL语句

db.execSQL(DATABASE_CREATE);

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

//判断数据库是否存在

db.execSQL("DROP TABLE IF EXISTS diary");

onCreate(db);

}

}

数据库增,删,改,查公共类:

Java代码

package us.imnet.iceskysl.db.notepad;

import java.util.Calendar;