继承SQLiteOpenHelper创建库增加表和删除表

public class Dbhelper extends SQLiteOpenHelper {public static final String name = "myname.db";public static final int version = 1;//创建数据库public Dbhelper(Context context) {super(context, name, null, version);}//创建表@Overridepublic void onCreate(SQLiteDatabase arg0) {// TODO Auto-generated method stubarg0.execSQL("create table  diary"+"("+"_idinteger primary key autoincrement,"+"topic   varchar(100),"+"content    varchar(1000)");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub//删除表db.execSQL("drop table if exists diary");//创建表onCreate(db);}}