编辑：可能值得补充的是，我在单独的 java 类中创建了 4/5 个表，这是正确的做事方式还是应该在 1 个类中创建所有表？
好的，我有多个表正在运行并在我的应用程序上工作。如果我想添加一个到目前为止一直在工作的新表，我被告知要从应用程序中擦除数据。
还添加了 if 语句检查也有效的 oldversion==1 方法。
我试图添加一个新表，突然我的一半表不起作用。有些会，有些不会，而且非常不一致。
这段代码是我用来在擦除之前成功运行我的表的代码，但是它不会创建表，因为它找不到名为“Achievements”的表
编辑 2：我已将所有表格归为 1 类，但仍然出现相同的错误：
MyDb.java
包 com.gofitness.www；
import java.sql.SQLException;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class MyDb {
public static final String KEY_USERID = "userid";
public static final String KEY_USERNAME = "username";
public static final String KEY_PASSWORD = "password";
public static final String KEY_WEIGHT = "weight";
public static final String KEY_HEIGHT = "height";
public static final String KEY_AGE = "age";
public static final String KEY_CALORIES = "calories";
public static final String KEY_PROTEIN = "protein";
public static final String KEY_CARBS = "carbs";
public static final String KEY_FATS = "fats";
public static final String KEY_ACHID = "AchievementID";
public static final String KEY_COMPLETED = "Completed";
public static final String KEY_ACH = "Achievement";
public static final String TAG = "MyDb";
private static final String DATABASE_NAME = "GoFitness";
private static final int DATABASE_VERSION = 1;
private static final String Create_Users =
"create table users (userid integer primary key autoincrement, "
+ "username text not null, password text not null);";
private static final String Create_Stats =
"create table stats (userid integer primary key autoincrement, "
+ KEY_USERNAME + " TEXT NOT NULL, " +
KEY_AGE + " INT NOT NULL, " +
KEY_CALORIES + " INT NOT NULL, " +
KEY_WEIGHT + " INT NOT NULL, " +
KEY_HEIGHT + " INT NOT NULL, " +
KEY_PROTEIN + " INT NOT NULL, " +
KEY_FATS + " INT NOT NULL, " +
KEY_CARBS + " INT NOT NULL);";
private static final String Create_Achievements =
"create table achievements (AchievementID integer primary key autoincrement, "
+ "Achievement text not null);";
private static final String Create_UserAchievements =
"create table userachievements (userid integer, "
+ "AchievementID integer not null, Completed text not null);";
private Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public MyDb(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(Create_Users);
db.execSQL(Create_Stats);
db.execSQL(Create_Achievements);
db.execSQL(Create_UserAchievements);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS users,stats,achievements,userachievements");
onCreate(db);
}
}
public MyDb open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
public long createEntry(String usernamevar, String agevar,String
weightvar,String heightvar,String caloriesvar,
String proteinvar, String carbsvar, String fatvar) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_USERNAME,usernamevar);
cv.put(KEY_AGE,agevar);
cv.put(KEY_WEIGHT,weightvar);
cv.put(KEY_HEIGHT,heightvar);
cv.put(KEY_CALORIES,caloriesvar);
cv.put(KEY_PROTEIN,proteinvar);
cv.put(KEY_CARBS,carbsvar);
cv.put(KEY_FATS,fatvar);
return db.insert("stats", null, cv);
}
public long createUA(String check, String checkpass, String completedDB) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_ACHID,check);
cv.put(KEY_USERID,checkpass);
cv.put(KEY_COMPLETED,completedDB);
return db.insert("userachievements",null, cv);
}
public long createAch(String check) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_ACH,check);
return db.insert("achievements",null, cv);
}
public long createUser(String check, String checkpass) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_USERNAME,check);
cv.put(KEY_PASSWORD,checkpass);
return db.insert("users",null, cv);
}
public String getName(String s) {
// TODO Auto-generated method stub
Cursor c = db.rawQuery("SELECT * FROM " +
"users" +
" where username = "+ "'"+ s+"'" , null);
if (c != null ) {
c.moveToFirst();
int iUsername = c.getColumnIndex(KEY_USERNAME);
String Name = c.getString(iUsername);
return Name;
}
return null;
}
public String getPass(String s) {
// TODO Auto-generated method stub
Cursor c = db.rawQuery("SELECT * FROM " +
"users" +
" where username = "+ "'"+ s+"'" , null);
if (c != null ) {
c.moveToFirst();
int iPassword = c.getColumnIndex(KEY_PASSWORD);
String Pass = c.getString(iPassword);
return Pass;
}
{
return null;
}
}
public String getId(String s) {
// TODO Auto-generated method stub
Cursor c = db.rawQuery("SELECT * FROM " +
"users" +
" where username = "+ "'"+ s+"'" , null);
if (c != null ) {
c.moveToFirst();
int iPassword = c.getColumnIndex(KEY_USERID);
String ID = c.getString(iPassword);
return ID;
}
{
return null;
}
}
}
成就.java
package com.gofitness.www;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Achievements extends Activity {
Button submit;
TextView invalid;
@Override
protected void onCreate(Bundle login) {
// TODO Auto-generated method stub
super.onCreate(login);
setContentView(R.layout.text);
Button submit = (Button) findViewById(R.id.submit);
final EditText username = (EditText) findViewById(R.id.etUsername);
final EditText password = (EditText) findViewById(R.id.etPassword);
final TextView invalid = (TextView) findViewById(R.id.invalid);
submit.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
boolean diditwork = true;
try {
String check = username.getText().toString();
String checkpass = password.getText().toString();
AddAchievements entry = new AddAchievements(Achievements.this);
entry.open();
entry.createEntry(check, checkpass);
entry.close();
}catch (Exception e){
diditwork=false;
}finally{
if(diditwork){
invalid.setText("WERKZ");
}
}
}
AddAchievements.java
package com.gofitness.www;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class AddAchievements {
public static final String KEY_ROWID = "AchievementID";
public static final String KEY_NAME = "Achievement";
private static final String DATABASE_NAME = "gofitness";
private static final String DATABASE_TABLE = "Achievements";
private static final int DATABASE_VERSION = 2;
private DbHelper ourHelper;
Context ourContext;
private SQLiteDatabase ourDatabase;
private static class DbHelper extends SQLiteOpenHelper
{
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(
"CREATE TABLE " + DATABASE_TABLE + "(" +
KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
KEY_NAME + " TEXT NOT NULL);"
);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
if (oldVersion==1){
db.execSQL("DROP TABLE IF EXISTS " +
DATABASE_TABLE);
onCreate(db);
}}
}
public AddAchievements(Context c)
{
ourContext = c;
}
public AddAchievements open(){
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close(){
ourHelper.close();
}
public long createEntry(String check, String checkpass) {
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_NAME,check);
return ourDatabase.insert(DATABASE_TABLE,null, cv);
}
public String getData() {
// TODO Auto-generated method stub
String[] columns = new String[]{KEY_ROWID, KEY_NAME};
Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(KEY_ROWID);
int iUser = c.getColumnIndex(KEY_NAME);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
result = result + c.getString(iRow) + " " + c.getString(iUser) +"\n";
}
return result;
}
public String getName(String s) {
// TODO Auto-generated method stub
Cursor c = ourDatabase.rawQuery("SELECT * FROM " +
DATABASE_TABLE +
" where username = "+ "'"+ s+"'" , null);
if (c != null ) {
c.moveToFirst();
int iUsername = c.getColumnIndex(KEY_NAME);
String Name = c.getString(iUsername);
return Name;
}
return null;
}
}
如果有人能指出我为什么这些不起作用，我将非常感激。谢谢
});
}
}