SQLite的访问表的内容

问题描述

我已经成功地使用下面的类表中插入的数据，但我不知道如何访问这些数据。另外，我想将数据表和数组列表的列内容，如

public class SQLiteAdapter {

 public static final String MYDATABASE_NAME = "MY_DATABASE";
 public static final String MYDATABASE_TABLE = "MY_TABLE";
 public static final int MYDATABASE_VERSION = 1;
 public static final String KEY_ID = "_id";
 public static final String KEY_CONTENT1 = "Content1";
 public static final String KEY_CONTENT2 = "Content2";
 public static final String KEY_CONTENT3 = "Content3";
 public static final String KEY_CONTENT4 = "Content4";



 //create table MY_DATABASE (ID integer primary key, Content text not null);
 private static final String SCRIPT_CREATE_DATABASE =
  "create table " + MYDATABASE_TABLE + " ("
  + KEY_ID + " integer primary key autoincrement, "
  + KEY_CONTENT1 + " text not null, "
  + KEY_CONTENT2 + " text not null, "
  + KEY_CONTENT3 + " text not null, "
  + KEY_CONTENT4 + " text not null);";

 private SQLiteHelper sqLiteHelper;
 private SQLiteDatabase sqLiteDatabase;

 private Context context;

 public SQLiteAdapter(Context c){

     this.context=c;
 }

 public SQLiteAdapter openToRead() throws android.database.SQLException {
  sqLiteHelper = new SQLiteHelper(context, MYDATABASE_NAME, null, MYDATABASE_VERSION);
  sqLiteDatabase = sqLiteHelper.getReadableDatabase();
  return this;
 }

 public SQLiteAdapter openToWrite() throws android.database.SQLException {
  sqLiteHelper = new SQLiteHelper(context, MYDATABASE_NAME, null, MYDATABASE_VERSION);
  sqLiteDatabase = sqLiteHelper.getWritableDatabase();
  return this;
 }

 public void close(){
  sqLiteHelper.close();
 }

 public long insert(String content1, String content2, String content3, String content4){

  ContentValues contentValues = new ContentValues();
  contentValues.put(KEY_CONTENT1, content1);
  contentValues.put(KEY_CONTENT2, content2);
  contentValues.put(KEY_CONTENT3, content3);
  contentValues.put(KEY_CONTENT4, content4);


  return sqLiteDatabase.insert(MYDATABASE_TABLE, null, contentValues);
 }

 public int deleteAll(){
  return sqLiteDatabase.delete(MYDATABASE_TABLE, null, null);
 }

 public Cursor queueAll(){
  String[] columns = new String[]{KEY_ID, KEY_CONTENT1, KEY_CONTENT2, KEY_CONTENT3, KEY_CONTENT4};
  Cursor cursor = sqLiteDatabase.query(MYDATABASE_TABLE, columns,
    null, null, null, null, null);

  return cursor;
 }

 public class SQLiteHelper extends SQLiteOpenHelper {

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

  @Override
  public void onCreate(SQLiteDatabase db) {
   // TODO Auto-generated method stub
   db.execSQL(SCRIPT_CREATE_DATABASE);
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
   // TODO Auto-generated method stub
  }
 }
}

解决方案

To have access to a database, try this.

First you must be having a class that extends your SQLiteOpenHelper. Create a new class which extends SQLiteOpenHelper and call them in main database opening class.

Here you go add these two chunks and call them in you onCreate method

public Cursor getShow()
{
    SQLiteDatabase db = obj.getReadableDatabase();
    Cursor c = db.rawQuery("select * from emp", null);
    startManagingCursor(c);
    return c;
}

public Cursor getEvent(Cursor c)
{
    StringBuilder sb= new StringBuilder("Data Base:-");
    while(c.moveToNext())
    {
        long id = c.getLong(0);
        String un = c.getString(1);
        String pw = c.getString(2);
        String ut = c.getString(3);
        sb.append("\n"+"id:-"+id+
            "\n"+"Username:-"+un+
            "\n"+"Password:-"+pw+"\n"+
            "\n"+"UserType:-"+ut+"\n"
        );
    }
    tvTools.setText(sb);
    return c;
}

This fetches three columns that i have created earlier and display them on TextView. Now call these method in onCreate().

Cursor c = getShow();
getEvent(c);

It works for me every time.

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