Android的 - SQLite数据库的方法未定义FOT类型 [英] Android - Sqlite database method undefined fot type

问题描述

我的类在这个应用程序，应该创建并使用一个数据库，但是Eclipse告诉我，sqlite的方法是不确定的。

i've a class in this app that should create and use a database, but Eclipse tell me that the sqlite methods are undefined.

似乎是一个环境问题，但我不知道如何解决，有我延长活动的不同类的呢？

Seem to be a context problem but i don't understand how to fix, have i to extend a different class instead of Activity?

package com.android.userdata;

import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

 public class getdata extends Activity {

  private final String MY_DATABASE_NAME = "DataStore";
        private final String MY_DATABASE_TABLE = "UserData";

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

         SQLiteDatabase myDB = null;
            /* Create the Database (no Errors if it already exists) */
            this.createDatabase(MY_DATABASE_NAME, 1, MODE_PRIVATE, null);
            myDB = this.openDatabase(MY_DATABASE_NAME, null);

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

         Button btn = (Button) findViewById(R.id.confirm);
         btn.setOnClickListener(new OnClickListener() {
          @Override
          public void onClick(View v) {
           Toast.makeText(getdata.this, "Hai Premuto il Pulsante", Toast.LENGTH_SHORT).show();
          }
         });
     }
}

感谢您的帮助！

Thanks for your help!

推荐答案

我建议你使用SQLiteOpenHelper。

I suggest you use the SQLiteOpenHelper.

它会自动关心创建一个数据库，如果它是不可用......

It cares automatically to create a DB if it's not available...

例如code：

 public class DatabaseHelper extends SQLiteOpenHelper {
     private static final int DB_VERSION = 1;
     private static final String DB_NAME = "myDB.db";

     public DatabaseHelper(Context ctx) {
         super(ctx, DB_NAME, null, DB_VERSION);
     }

     @Override
     public void onCreate(SQLiteDatabase db) {
         String query = "CREATE TABLE myTable(_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, age INTEGER NOT NULL)";
         db.execSQL(query);
         db.close();
     }

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

使用方法如下：

...
DatabaseHelper helper = new DatabaseHelper(context);
SQLiteDatabase db = helper.getWritableDatabase();
...

我认为这是更简单，你不需要关心，如果数据库是存在的了。

I think it's easier and you don't need to care about if the DB is existing already.

希望这有助于：）

编辑：

我有一个想法......也许这是不可能把这个字符串像你这样做...尝试之前建立的字符串。 像这样的：

I have an idea... maybe it is not possible to give this string like you are doing... try to build the string before. Like this:

String query = "YOUR SQL STATEMENT";
db.execSQL(query);
db.close();

这样的可能性：）

Is a possibility :)

这篇关于Android的 - SQLite数据库的方法未定义FOT类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！