Java 如何在android中使用SQLite？

我已经找到了这个主题的一些答案（例如），但它不起作用。我只得到警告，它无法解析方法“openOrCreateDatabase（java.lang.String，int，null）”

以下是我的源代码：

public class DBHandler
{
    SQLiteDatabase database;
    DBHandler()
    {
        database = openOrCreateDatabase("DatabaseName", Context.MODE_PRIVATE, null);
    }
}

是一个开源SQL数据库，将数据存储到设备上的文本文件中。Android自带了内置的SQLite数据库实现

请查看以下链接

结构

 public class MySQLiteHelper extends SQLiteOpenHelper {

  public static final String TABLE_COMMENTS = "comments";
  public static final String COLUMN_ID = "_id";
  public static final String COLUMN_COMMENT = "comment";

  private static final String DATABASE_NAME = "commments.db";
  private static final int DATABASE_VERSION = 1;

  // Database creation sql statement
  private static final String DATABASE_CREATE = "create table "
      + TABLE_COMMENTS + "(" + COLUMN_ID
      + " integer primary key autoincrement, " + COLUMN_COMMENT
      + " text not null);";

  public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase database) {
    database.execSQL(DATABASE_CREATE);
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(MySQLiteHelper.class.getName(),
        "Upgrading database from version " + oldVersion + " to "
            + newVersion + ", which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_COMMENTS);
    onCreate(db);
  }

} 

是一个开源SQL数据库，将数据存储到设备上的文本文件中。Android自带了内置的SQLite数据库实现

请查看以下链接

结构

 public class MySQLiteHelper extends SQLiteOpenHelper {

  public static final String TABLE_COMMENTS = "comments";
  public static final String COLUMN_ID = "_id";
  public static final String COLUMN_COMMENT = "comment";

  private static final String DATABASE_NAME = "commments.db";
  private static final int DATABASE_VERSION = 1;

  // Database creation sql statement
  private static final String DATABASE_CREATE = "create table "
      + TABLE_COMMENTS + "(" + COLUMN_ID
      + " integer primary key autoincrement, " + COLUMN_COMMENT
      + " text not null);";

  public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase database) {
    database.execSQL(DATABASE_CREATE);
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(MySQLiteHelper.class.getName(),
        "Upgrading database from version " + oldVersion + " to "
            + newVersion + ", which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_COMMENTS);
    onCreate(db);
  }

} 

---

正如注释者给出的示例，您将需要创建SQLiteOpenHelper类的子类，并重写将创建数据库和表的onCreate和onUpgrade方法。然后，您可以使用这个helper类的getReadableDatabase（）或getWriteableDatabase（）方法来获取SQLite数据库的副本。您可以在此对象上执行查询。 下面的代码片段演示了这一点

public class DBAdapter {
private SQLiteDatabase database;
private Context context;
private DatabaseHelper dbHelper;


private class DatabaseHelper extends SQLiteOpenHelper {

    public DatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLES_QUERY);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXIST "+TABLE_QUERY);
    }
}

public DBAdapter(Context ctx) {
    this.context = ctx;

}

public DBAdapter open() throws SQLException {
    dbHelper = new DatabaseHelper(context, DBNAME, null,DBVERSION);
    database = dbHelper.getWritableDatabase();
    return this;
}

public Cursor executeQuery() {
    Cursor result = database.rawQuery(YOUR_QUERY, null);
    return result;
}

}

使用它可以获得更多帮助

---

我希望这会有所帮助。

正如评论员给您提供的示例一样，您需要创建SQLiteOpenHelper类的子类，并重写将创建数据库和表的onCreate和onUpgrade方法。然后，您可以使用这个helper类的getReadableDatabase（）或getWriteableDatabase（）方法来获取SQLite数据库的副本。您可以在此对象上执行查询。 下面的代码片段演示了这一点

public class DBAdapter {
private SQLiteDatabase database;
private Context context;
private DatabaseHelper dbHelper;


private class DatabaseHelper extends SQLiteOpenHelper {

    public DatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLES_QUERY);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXIST "+TABLE_QUERY);
    }
}

public DBAdapter(Context ctx) {
    this.context = ctx;

}

public DBAdapter open() throws SQLException {
    dbHelper = new DatabaseHelper(context, DBNAME, null,DBVERSION);
    database = dbHelper.getWritableDatabase();
    return this;
}

public Cursor executeQuery() {
    Cursor result = database.rawQuery(YOUR_QUERY, null);
    return result;
}

}

使用它可以获得更多帮助

---

我希望它能有所帮助。

使用下面的示例创建数据库

 import android.content.ContentValues;
        import android.content.Context;
        import android.database.sqlite.SQLiteDatabase;
        import android.database.sqlite.SQLiteOpenHelper;
        import android.util.Log;

        import com.ayconsultancy.sumeshmedicals.SumeshMedicalContext;
        import com.ayconsultancy.sumeshmedicals.model.PlaceModel;
        import com.ayconsultancy.sumeshmedicals.utils.Utils;

        import org.json.JSONArray;
        import org.json.JSONException;
        import org.json.JSONObject;

        import java.util.ArrayList;

        /**
         * Created by Admin33 on 16-02-2016.
         */
        public class DBHelper extends SQLiteOpenHelper {
            static String DATABASE_NAME = "sumesh_medicals";
            static int DATABASE_VERSION = 1;
            static DBHelper dbHelperInstance;
            static SQLiteDatabase db;

            public DBHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            public static DBHelper getInstance() {
                if (dbHelperInstance == null) {
                    dbHelperInstance = new DBHelper(SumeshMedicalContext.getContext());
                }
                return dbHelperInstance;
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                Utils.ShowLogD("in sqlite oncreate");
                try {
                    db.execSQL(DBQueries.CREATE_OTC_TABLE);
                    db.execSQL(DBQueries.CREATE_SHOP_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_USER_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_CITY_TABLE);
                } catch (Exception e) {
                    e.printStackTrace();
                }

               // insertIntoShopDetails(db);
                //  insertIntoOTcPrescrion(db);

            }

            public synchronized SQLiteDatabase getDababase() {
                if (db == null || (db != null && !db.isOpen())) {
                    db = this.getWritableDatabase();
                }
                return db;
            }

            public synchronized void close() {
                super.close();
                if (db != null)
                    db.close();
            }

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

            }
}

---

使用下面的示例创建数据库

 import android.content.ContentValues;
        import android.content.Context;
        import android.database.sqlite.SQLiteDatabase;
        import android.database.sqlite.SQLiteOpenHelper;
        import android.util.Log;

        import com.ayconsultancy.sumeshmedicals.SumeshMedicalContext;
        import com.ayconsultancy.sumeshmedicals.model.PlaceModel;
        import com.ayconsultancy.sumeshmedicals.utils.Utils;

        import org.json.JSONArray;
        import org.json.JSONException;
        import org.json.JSONObject;

        import java.util.ArrayList;

        /**
         * Created by Admin33 on 16-02-2016.
         */
        public class DBHelper extends SQLiteOpenHelper {
            static String DATABASE_NAME = "sumesh_medicals";
            static int DATABASE_VERSION = 1;
            static DBHelper dbHelperInstance;
            static SQLiteDatabase db;

            public DBHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            public static DBHelper getInstance() {
                if (dbHelperInstance == null) {
                    dbHelperInstance = new DBHelper(SumeshMedicalContext.getContext());
                }
                return dbHelperInstance;
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                Utils.ShowLogD("in sqlite oncreate");
                try {
                    db.execSQL(DBQueries.CREATE_OTC_TABLE);
                    db.execSQL(DBQueries.CREATE_SHOP_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_USER_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_CITY_TABLE);
                } catch (Exception e) {
                    e.printStackTrace();
                }

               // insertIntoShopDetails(db);
                //  insertIntoOTcPrescrion(db);

            }

            public synchronized SQLiteDatabase getDababase() {
                if (db == null || (db != null && !db.isOpen())) {
                    db = this.getWritableDatabase();
                }
                return db;
            }

            public synchronized void close() {
                super.close();
                if (db != null)
                    db.close();
            }

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

            }
}

---

要将数据保存到sqlite中，请使用以下main中的first

public class MainActivity extends AppCompatActivity {

String one,two;
EditText name,phone;
Button saveButton;
List<StudentModel> list = new ArrayList<StudentModel>();
DatabaseHelper db;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    db = new DatabaseHelper(getApplicationContext());

    saveButton=(Button)findViewById(R.id.submit);
    name=(EditText)findViewById(R.id.textName);
    phone=(EditText)findViewById(R.id.textPhone);

    saveButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            StudentModel student = new StudentModel();
            student.name = name.getText().toString();
            student.phone_number = phone.getText().toString();
            db.addStudentDetail(student);

            list = db.getAllStudentsList();
            print(list);




        }
    });
}
private void print(List<StudentModel> list) {

    String value = "";
    for(StudentModel sm : list){
        value = value+"id: "+sm.id+", name: "+sm.name+" Ph_no: "+sm.phone_number+"\n";
    }

    Log.i("<<<<<<<<<<",value);

}


}

---

尝试使用以下方法将数据保存到sqlite中

public class MainActivity extends AppCompatActivity {

String one,two;
EditText name,phone;
Button saveButton;
List<StudentModel> list = new ArrayList<StudentModel>();
DatabaseHelper db;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    db = new DatabaseHelper(getApplicationContext());

    saveButton=(Button)findViewById(R.id.submit);
    name=(EditText)findViewById(R.id.textName);
    phone=(EditText)findViewById(R.id.textPhone);

    saveButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            StudentModel student = new StudentModel();
            student.name = name.getText().toString();
            student.phone_number = phone.getText().toString();
            db.addStudentDetail(student);

            list = db.getAllStudentsList();
            print(list);




        }
    });
}
private void print(List<StudentModel> list) {

    String value = "";
    for(StudentModel sm : list){
        value = value+"id: "+sm.id+", name: "+sm.name+" Ph_no: "+sm.phone_number+"\n";
    }

    Log.i("<<<<<<<<<<",value);

}


}

---

试试看

这是我的代码，告诉你如何使用sqlite数据库

 import android.content.ContentValues;
        import android.content.Context;
        import android.database.sqlite.SQLiteDatabase;
        import android.database.sqlite.SQLiteOpenHelper;
        import android.util.Log;

        import com.ayconsultancy.sumeshmedicals.SumeshMedicalContext;
        import com.ayconsultancy.sumeshmedicals.model.PlaceModel;
        import com.ayconsultancy.sumeshmedicals.utils.Utils;

        import org.json.JSONArray;
        import org.json.JSONException;
        import org.json.JSONObject;

        import java.util.ArrayList;

        /**
         * Created by Admin33 on 16-02-2016.
         */
        public class DBHelper extends SQLiteOpenHelper {
            static String DATABASE_NAME = "sumesh_medicals";
            static int DATABASE_VERSION = 1;
            static DBHelper dbHelperInstance;
            static SQLiteDatabase db;

            public DBHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            public static DBHelper getInstance() {
                if (dbHelperInstance == null) {
                    dbHelperInstance = new DBHelper(SumeshMedicalContext.getContext());
                }
                return dbHelperInstance;
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                Utils.ShowLogD("in sqlite oncreate");
                try {
                    db.execSQL(DBQueries.CREATE_OTC_TABLE);
                    db.execSQL(DBQueries.CREATE_SHOP_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_USER_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_CITY_TABLE);
                } catch (Exception e) {
                    e.printStackTrace();
                }

               // insertIntoShopDetails(db);
                //  insertIntoOTcPrescrion(db);

            }

            public synchronized SQLiteDatabase getDababase() {
                if (db == null || (db != null && !db.isOpen())) {
                    db = this.getWritableDatabase();
                }
                return db;
            }

            public synchronized void close() {
                super.close();
                if (db != null)
                    db.close();
            }

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

            }
}

DatabaseHelper.java

            public class DatabaseHelper extends SQLiteOpenHelper {

                    public DatabaseHelper(Context context) {
                        super(context, "loginDB.db", null, 1);
                        getWritableDatabase();
                    }

                    @Override
                    public void onCreate(SQLiteDatabase sqLiteDatabase) {
                        String query = "create table registration (id INTEGER,Image BLOB,firstname VARCHAR,Lastname VARCHAR,DateOfBirth VARCHAR,Phone VARCHAR,Gender VARCHAR, Email VARCHAR primary key,Password VARCHAR);";
                        sqLiteDatabase.execSQL(query);
                    }

                    @Override
                    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

                    }
            //method for insert data
            public boolean insertRecord(byte[] imageInByte,String fn) {
                SQLiteDatabase db = this.getWritableDatabase();
                ContentValues contentValues = new ContentValues();
                contentValues.put("Image", imageInByte);
                contentValues.put("Firstname", fn);
                db.insert("signup", null, contentValues);
                return true;
            }

       public boolean updaterecord(String fn,String ln,String unme){
                SQLiteDatabase db = this.getWritableDatabase();
                ContentValues contentValues = new ContentValues();
                contentValues.put("Firstname", fn);
                contentValues.put("Lastname", ln);
                contentValues.put("Username", unme);
                return db.update(TABLE_NAME, contentValues, "Username = ?", new String[]{(unme)}) > 0;
            }

public boolean deleterecord(String FirstName) {

            SQLiteDatabase db = this.getWritableDatabase();
            return db.delete(TABLE_NAME, "Firstname = ?", new String[]{FirstName}) > 0;
        }

             public int displayDetail(String email, String password) {
                    SQLiteDatabase db = this.getWritableDatabase();
                    Cursor cursor = db.rawQuery("select * from registration where Email='" + email + "'AND Password='" + password + "'", null);

                    return cursor.getCount();
                }

                public ArrayList displayDetails(String email, String password) {
                    SQLiteDatabase db = this.getWritableDatabase();
                    Cursor cursor = db.rawQuery("select * from registration where Email='" + email + "'AND Password='" + password + "'", null);

                    ArrayList<ModelClass> arrayList = new ArrayList();
                    ModelClass model;
                    if (cursor != null) {
                        if (cursor.getCount() > 0) {
                            while (cursor.moveToNext()) {
                                model = new Model();
                                model.setFirstname(cursor.getString(cursor.getColumnIndex("Firstname")));
                                model.setLastname(cursor.getString(cursor.getColumnIndex("Lastname")));
                                arrayList.add(model);
                            }
                        }
                    }
                    return arrayList;
                }
                }

public类DatabaseHelper扩展了SQLiteOpenHelper{
公共数据库助手（上下文）{
super（上下文“loginDB.db”，null，1）；
getWritableDatabase（）；
}
@凌驾
public void onCreate（SQLiteDatabase SQLiteDatabase）{
String query=“创建表注册（id INTEGER、Image BLOB、firstname VARCHAR、Lastname VARCHAR、DateOfBirth VARCHAR、Phone VARCHAR、Gender VARCHAR、Email VARCHAR主键、Password VARCHAR）；”；
execSQL（查询）；
}
@凌驾
public void onUpgrade（SQLiteDatabase SQLiteDatabase，inti，inti1）{
}
//插入数据的方法
公共布尔插入记录（字节[]imageInByte，字符串fn）{
SQLiteDatabase db=this.getWritableDatabase（）；
ContentValues ContentValues=新ContentValues（）；
contentValues.put（“图像”，imageInByte）；
contentValues.put（“Firstname”，fn）；
db.insert（“signup”，null，contentValues）；
返回true；
}
公共布尔更新记录（字符串fn、字符串ln、字符串埃厄特派团）{
SQLiteDatabase db=this.getWritableDatabase（）；
ContentValues ContentValues=新ContentValues（）；
contentValues.put（“Firstname”，fn）；
contentValues.put（“Lastname”，ln）；
contentValues.put（“用户名”，埃厄特派团）；
返回db.update（TABLE_NAME，contentValues，“Username=？”，新字符串[]{（埃厄特派团）}>0；
}
公共布尔deleterecord（字符串名）{
SQLiteDatabase db=this.getWritableDatabase（）；
返回db.delete（表_NAME，“Firstname=？”，新字符串[]{Firstname}）>0；
}
public int displayDetail（字符串电子邮件、字符串密码）{
SQLiteDatabase db=this.getWritableDatabase（）；
Cursor Cursor=db.rawQuery（“从注册中选择*，其中Email='”+Email+“'和Password='“+Password+””，null）；
返回cursor.getCount（）；
}
公共ArrayList显示详细信息（字符串电子邮件、字符串密码）{
SQLiteDatabase db=this.getWritableDatabase（）；
Cursor Cursor=db.rawQuery（“从注册中选择*，其中Email='”+Email+“'和Password='“+Password+””，null）；
ArrayList ArrayList=新的ArrayList（）；
模型类模型；
如果（光标！=null）{
if（cursor.getCount（）>0）{
while（cursor.moveToNext（））{
模型=新模型（）；
model.setFirstname（cursor.getString（cursor.getColumnIndex（“Firstname”））；
model.setLastname（cursor.getString（cursor.getColumnIndex（“Lastname”））；
arrayList.add（模型）；
}
}
}
返回数组列表；
}
}

以下是我如何使用sqlite数据库的代码

 import android.content.ContentValues;
        import android.content.Context;
        import android.database.sqlite.SQLiteDatabase;
        import android.database.sqlite.SQLiteOpenHelper;
        import android.util.Log;

        import com.ayconsultancy.sumeshmedicals.SumeshMedicalContext;
        import com.ayconsultancy.sumeshmedicals.model.PlaceModel;
        import com.ayconsultancy.sumeshmedicals.utils.Utils;

        import org.json.JSONArray;
        import org.json.JSONException;
        import org.json.JSONObject;

        import java.util.ArrayList;

        /**
         * Created by Admin33 on 16-02-2016.
         */
        public class DBHelper extends SQLiteOpenHelper {
            static String DATABASE_NAME = "sumesh_medicals";
            static int DATABASE_VERSION = 1;
            static DBHelper dbHelperInstance;
            static SQLiteDatabase db;

            public DBHelper(Context context) {
                super(context, DATABASE_NAME, null, DATABASE_VERSION);
            }

            public static DBHelper getInstance() {
                if (dbHelperInstance == null) {
                    dbHelperInstance = new DBHelper(SumeshMedicalContext.getContext());
                }
                return dbHelperInstance;
            }

            @Override
            public void onCreate(SQLiteDatabase db) {
                Utils.ShowLogD("in sqlite oncreate");
                try {
                    db.execSQL(DBQueries.CREATE_OTC_TABLE);
                    db.execSQL(DBQueries.CREATE_SHOP_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_USER_DETAILS_TABLE);
                    db.execSQL(DBQueries.CREATE_CITY_TABLE);
                } catch (Exception e) {
                    e.printStackTrace();
                }

               // insertIntoShopDetails(db);
                //  insertIntoOTcPrescrion(db);

            }

            public synchronized SQLiteDatabase getDababase() {
                if (db == null || (db != null && !db.isOpen())) {
                    db = this.getWritableDatabase();
                }
                return db;
            }

            public synchronized void close() {
                super.close();
                if (db != null)
                    db.close();
            }

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

            }
}

DatabaseHelper.java

            public class DatabaseHelper extends SQLiteOpenHelper {

                    public DatabaseHelper(Context context) {
                        super(context, "loginDB.db", null, 1);
                        getWritableDatabase();
                    }

                    @Override
                    public void onCreate(SQLiteDatabase sqLiteDatabase) {
                        String query = "create table registration (id INTEGER,Image BLOB,firstname VARCHAR,Lastname VARCHAR,DateOfBirth VARCHAR,Phone VARCHAR,Gender VARCHAR, Email VARCHAR primary key,Password VARCHAR);";
                        sqLiteDatabase.execSQL(query);
                    }

                    @Override
                    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

                    }
            //method for insert data
            public boolean insertRecord(byte[] imageInByte,String fn) {
                SQLiteDatabase db = this.getWritableDatabase();
                ContentValues contentValues = new ContentValues();
                contentValues.put("Image", imageInByte);
                contentValues.put("Firstname", fn);
                db.insert("signup", null, contentValues);
                return true;
            }

       public boolean updaterecord(String fn,String ln,String unme){
                SQLiteDatabase db = this.getWritableDatabase();
                ContentValues contentValues = new ContentValues();
                contentValues.put("Firstname", fn);
                contentValues.put("Lastname", ln);
                contentValues.put("Username", unme);
                return db.update(TABLE_NAME, contentValues, "Username = ?", new String[]{(unme)}) > 0;
            }

public boolean deleterecord(String FirstName) {

            SQLiteDatabase db = this.getWritableDatabase();
            return db.delete(TABLE_NAME, "Firstname = ?", new String[]{FirstName}) > 0;
        }

             public int displayDetail(String email, String password) {
                    SQLiteDatabase db = this.getWritableDatabase();
                    Cursor cursor = db.rawQuery("select * from registration where Email='" + email + "'AND Password='" + password + "'", null);

                    return cursor.getCount();
                }

                public ArrayList displayDetails(String email, String password) {
                    SQLiteDatabase db = this.getWritableDatabase();
                    Cursor cursor = db.rawQuery("select * from registration where Email='" + email + "'AND Password='" + password + "'", null);

                    ArrayList<ModelClass> arrayList = new ArrayList();
                    ModelClass model;
                    if (cursor != null) {
                        if (cursor.getCount() > 0) {
                            while (cursor.moveToNext()) {
                                model = new Model();
                                model.setFirstname(cursor.getString(cursor.getColumnIndex("Firstname")));
                                model.setLastname(cursor.getString(cursor.getColumnIndex("Lastname")));
                                arrayList.add(model);
                            }
                        }
                    }
                    return arrayList;
                }
                }

public类DatabaseHelper扩展了SQLiteOpenHelper{
公共数据库助手（上下文）{
super（上下文“loginDB.db”，null，1）；
getWritableDatabase（）；
}
@凌驾
public void onCreate（SQLiteDatabase SQLiteDatabase）{
String query=“创建表注册（id整数、图像BLOB、firstname VARCHAR、Lastname VARCHAR、DateOfBirth VARCHAR、Phone VAR