android - 如何在android中使用数据库？

Question

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Answer 1

其中一种方法是如下扩展 SQLiteOpenHelper 并覆盖 onCreate 以创建数据库。下面是一个简单的例子。

public class DBHelper extends SQLiteOpenHelper {

  private static String DB_NAME = "example.db";
  private static int DB_VERSION = 1;

  public DBHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase db) {
   db.execSQL("CREATE TABLE props (name TEXT PRIMARY KEY, value TEXT);");
INTEGER);");
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO: Write upgrade db scripts

  }
}

然后你可以像这样查询

SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
qb.setTables("PROPS");
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor c = qb.query(db, new String[]{"value"}, "name = '" + name +"'", null, null, null, null);
if(c.getCount() > 0) {
  c.moveToFirst();
  val = c.getString(c.getColumnIndexOrThrow("value"));
}
closeDbAndCursor(db,c);