从SQLite数据库中删除内容

Question

我想从SQLite数据库中删除所有表。问题是我似乎无法通过SQLite命令执行它，并且无法在我的计算机上找到这些文件。我有以下代码将数据插入到数据库中。

package com.example.mycoursetimetable; 


import java.util.ArrayList; 
import java.util.HashMap; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 

public class DBTools extends SQLiteOpenHelper { 

public DBTools(Context applicationContext){ 

    super(applicationContext, "module.db", null, 1); 

} 

@Override 
public void onCreate(SQLiteDatabase database) { 

    String query = "CREATE TABLE modules (moduleId INTEGER PRIMARY KEY,ModuleCode TEXT PRIMARY KEY, ModuleName TEXT,ModuleType TEXT, DayOfWeek TEXT, StartTime TEXT, EndTime TEXT,Location TEXT,AdditionalInfo Text)"; 

    database.execSQL(query); 

} 

@Override 
public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) { 

    String query = "DROP TABLE IF EXISTS modules"; 

    database.execSQL(query); 
    onCreate(database); 

} 

public void insertModule(HashMap<String, String> queryValues){ 

    SQLiteDatabase database = this.getWritableDatabase(); 

    ContentValues values = new ContentValues(); 

    values.put("ModuleCode", queryValues.get("ModuleCode")); 
    values.put("ModuleName", queryValues.get("ModuleName")); 
    values.put("ModuleType", queryValues.get("ModuleType")); 
    values.put("DayOfWeek", queryValues.get("DayOfWeek")); 
    values.put("StartTime", queryValues.get("StartTime")); 
    values.put("EndTime", queryValues.get("EndTime")); 
    values.put("Location", queryValues.get("Location")); 
    values.put("AdditionalInfo", queryValues.get("AdditionalInfo")); 

    database.insert("modules", null, values); 

    database.close(); 

} 

public int updateModule(HashMap<String, String> queryValues){ 

    SQLiteDatabase database = this.getWritableDatabase(); 

    ContentValues values = new ContentValues(); 


    values.put("ModuleCode", queryValues.get("ModuleCode")); 
    values.put("ModuleName", queryValues.get("ModuleName")); 
    values.put("ModuleType", queryValues.get("ModuleType")); 
    values.put("DayOfWeek", queryValues.get("DayOfWeek")); 
    values.put("StartTime", queryValues.get("StartTime")); 
    values.put("EndTime", queryValues.get("EndTime")); 
    values.put("Location", queryValues.get("Location")); 
    values.put("AdditionalInfo", queryValues.get("AdditionalInfo")); 

    return database.update("modules", values, 
      "moduleId" + " = ?", new String[] {queryValues.get("moduleId") }); 

} 

public void deleteModule(String id){ 

    SQLiteDatabase database = this.getWritableDatabase(); 

    String deleteQuery = "DELETE FROM modules WHERE moduleId='" + id + "'"; 

    database.execSQL(deleteQuery); 

} 

public ArrayList<HashMap<String, String>> getAllModules(){ 

    ArrayList<HashMap<String, String>> moduleArrayList = new ArrayList<HashMap<String, String>>(); 

    String selectQuery = "SELECT * FROM modules ORDER BY ModuleCode"; 

    SQLiteDatabase database = this.getWritableDatabase(); 

    Cursor cursor = database.rawQuery(selectQuery, null); 

    if(cursor.moveToFirst()){ 

     do{ 

      HashMap<String, String> moduleMap = new HashMap<String, String>(); 

      moduleMap.put("moduleId", cursor.getString(0)); 
      moduleMap.put("ModuleCode", cursor.getString(1)); 
      moduleMap.put("ModuleName", cursor.getString(2)); 
      moduleMap.put("ModuleType", cursor.getString(3)); 
      moduleMap.put("DayOfWeek", cursor.getString(4)); 
      moduleMap.put("StartTime", cursor.getString(5)); 
      moduleMap.put("EndTime", cursor.getString(6)); 
      moduleMap.put("Location", cursor.getString(7)); 
    //  moduleMap.put("AdditionalInfo", cursor.getString(8)); 


      moduleArrayList.add(moduleMap); 

     } while(cursor.moveToNext()); 

    } 

    return moduleArrayList; 

} 

public HashMap<String, String> getModuleInfo(String id){ 

    HashMap<String, String> moduleMap = new HashMap<String, String>(); 

    SQLiteDatabase database = this.getReadableDatabase(); 

    String selectQuery = "SELECT * FROM modules WHERE moduleId='" + id + "'"; 

    Cursor cursor = database.rawQuery(selectQuery, null); 

    if(cursor.moveToFirst()){ 

     do{ 

      moduleMap.put("moduleId", cursor.getString(0)); 
      moduleMap.put("ModuleCode", cursor.getString(1)); 
      moduleMap.put("ModuleName", cursor.getString(2)); 
      moduleMap.put("ModuleType", cursor.getString(3)); 
      moduleMap.put("DayOfWeek", cursor.getString(4)); 
      moduleMap.put("StartTime", cursor.getString(5)); 
      moduleMap.put("EndTime", cursor.getString(6)); 
      moduleMap.put("Location", cursor.getString(7)); 
     // moduleMap.put("AdditionalInfo", cursor.getString(8)); 


     } while(cursor.moveToNext()); 

    } 

    return moduleMap; 

} 

} 

从SQLite的外壳，我都以各种方式来选择我的数据库中的表试过很多次。它一直说没有这样的表，但数据在我的应用程序在启动。有没有人知道我怎么能摆脱这些表？

TIA

Answer 1

如果你真的要删除整个数据库的内容，包括它的结构（表），比最简单的方法是删除数据库并重新创建它。

下降与context.deleteDatabase(name)并重新创建只需打开它与Db开放助手。

deleteDatabase非常有用，例如，测试创建数据库代码时。

删除并重新创建数据库可确保不会留下任何内部结构或任何内容。这是一个干净的新开始。