我正在尝试从 SQLite 数据库中删除所有表。问题是我似乎无法通过 SQLite 命令执行此操作，并且在我的计算机上找不到文件。我有以下代码将数据插入数据库。
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;
}
}
在 SQLite shell 中，我多次尝试以各种方式选择数据库中的表。它一直说没有这样的表，但数据在我的应用程序启动时就在那里。有谁知道我怎样才能摆脱这些桌子？
TIA