Android 如何在每次运行后清除数据库中的数据？

如何在每次运行后清除数据库中的所有数据，或者换句话说，在每次运行应用程序时启动一个新数据库？

请查看此代码，最后一部分是清除数据库。同样，您需要实现您的逻辑

package com.collabera.labs.sai.db;

import java.util.ArrayList;

import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;

public class CRUDonDB extends ListActivity {

    private final String SAMPLE_DB_NAME = "myFriendsDb";
    private final String SAMPLE_TABLE_NAME = "friends";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        ArrayList<String> results = new ArrayList<String>();
        SQLiteDatabase sampleDB = null;

        try {
            sampleDB =  this.openOrCreateDatabase(SAMPLE_DB_NAME, MODE_PRIVATE, null);

            sampleDB.execSQL("CREATE TABLE IF NOT EXISTS " +
                    SAMPLE_TABLE_NAME +
                    " (LastName VARCHAR, FirstName VARCHAR," +
                    " Country VARCHAR, Age INT(3));");

            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Makam','Sai Geetha','India',25);");
            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Chittur','Raman','India',25);");
            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Solutions','Collabera','India',20);");

            Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM " +
                    SAMPLE_TABLE_NAME +
                    " where Age > 10 LIMIT 5", null);

            if (c != null ) {
                if  (c.moveToFirst()) {
                    do {
                        String firstName = c.getString(c.getColumnIndex("FirstName"));
                        int age = c.getInt(c.getColumnIndex("Age"));
                        results.add("" + firstName + ",Age: " + age);
                    }while (c.moveToNext());
                } 
            }

            this.setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,results));

        } catch (SQLiteException se ) {
            Log.e(getClass().getSimpleName(), "Could not create or Open the database");
        } finally {
            if (sampleDB != null) 
                sampleDB.execSQL("DELETE FROM " + SAMPLE_TABLE_NAME);
                sampleDB.close();
        }
    }
}

---

请看这段代码，在最后一部分它是清除数据库。同样，您需要实现您的逻辑

package com.collabera.labs.sai.db;

import java.util.ArrayList;

import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;

public class CRUDonDB extends ListActivity {

    private final String SAMPLE_DB_NAME = "myFriendsDb";
    private final String SAMPLE_TABLE_NAME = "friends";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        ArrayList<String> results = new ArrayList<String>();
        SQLiteDatabase sampleDB = null;

        try {
            sampleDB =  this.openOrCreateDatabase(SAMPLE_DB_NAME, MODE_PRIVATE, null);

            sampleDB.execSQL("CREATE TABLE IF NOT EXISTS " +
                    SAMPLE_TABLE_NAME +
                    " (LastName VARCHAR, FirstName VARCHAR," +
                    " Country VARCHAR, Age INT(3));");

            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Makam','Sai Geetha','India',25);");
            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Chittur','Raman','India',25);");
            sampleDB.execSQL("INSERT INTO " +
                    SAMPLE_TABLE_NAME +
                    " Values ('Solutions','Collabera','India',20);");

            Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM " +
                    SAMPLE_TABLE_NAME +
                    " where Age > 10 LIMIT 5", null);

            if (c != null ) {
                if  (c.moveToFirst()) {
                    do {
                        String firstName = c.getString(c.getColumnIndex("FirstName"));
                        int age = c.getInt(c.getColumnIndex("Age"));
                        results.add("" + firstName + ",Age: " + age);
                    }while (c.moveToNext());
                } 
            }

            this.setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,results));

        } catch (SQLiteException se ) {
            Log.e(getClass().getSimpleName(), "Could not create or Open the database");
        } finally {
            if (sampleDB != null) 
                sampleDB.execSQL("DELETE FROM " + SAMPLE_TABLE_NAME);
                sampleDB.close();
        }
    }
}

---

只需在每次运行时删除表中的所有行，并在需要时插入新的dataq

按照以下方法删除表中的所有数据

void deleteAllData()
{
    SQLiteDatabase sdb= this.getWritableDatabase();
    sdb.delete(tablename, null, null);

}

---

只需在每次运行时删除表中的所有行，并在需要时插入新的dataq

按照以下方法删除表中的所有数据

void deleteAllData()
{
    SQLiteDatabase sdb= this.getWritableDatabase();
    sdb.delete(tablename, null, null);

}

---

“运行”这个词在执行会话的意义上并不像在更常见的上下文中对程序那样适用于android。你将不得不考虑在活动生命周期中的什么地方进行这种清理是合适的。运行这个词在执行会话的意义上并不像在更常见的上下文中对程序那样适用于android。您将不得不考虑在活动生命周期中的什么地方进行这种清理是合适的。