Question

我想从数据库中检索所有事件名称，并希望将其添加到另一个活动中定义的Listview中。我有这个代码，但它是用于根据特定事件名称搜索数据。我想要检索所有这些

public class MyDBHandler extends SQLiteOpenHelper{

private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "eventDB.db";
private static final String TABLE_EVENTS = "events";

public static final String COLUMN_ID = "id";
public static final String COLUMN_EVENTNAME = "eventname";
public static final String COLUMN_TYPE = "type";
public static final String COLUMN_QUANTITY = "quantity";
public static final String COLUMN_PRICE ="price";
public static final String COLUMN_DATE ="date";
public static final String COLUMN_TIME = "time";
public MyDBHandler(Context context, String name,     SQLiteDatabase.CursorFactory factory, int version) {
    super(context, name, factory, version);
}

@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_EVENT_TABLE = "CREATE TABLE " +
            TABLE_EVENTS + "("
            + COLUMN_ID + " INTEGER PRIMARY KEY," + COLUMN_EVENTNAME
            + " TEXT," + COLUMN_TYPE + " TEXT,"+COLUMN_QUANTITY+" TEXT," +COLUMN_PRICE+ " TEXT,"+COLUMN_DATE + "TEXT," + COLUMN_TIME + "TEXT" + ")";
    db.execSQL(CREATE_EVENT_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_EVENTS);
    onCreate(db);
}
public void add_events(Event_Data event_data)
{
    ContentValues values = new ContentValues();
    values.put(COLUMN_EVENTNAME, event_data.getEventName());
    values.put(COLUMN_TYPE, event_data.getType());
    values.put(COLUMN_QUANTITY, event_data.getQuantity());
    values.put(COLUMN_PRICE, event_data.getPrice());
    values.put(COLUMN_DATE, event_data.getDate());
    values.put(COLUMN_TIME, event_data.getTim());

    SQLiteDatabase db = this.getWritableDatabase();

    db.insert(TABLE_EVENTS, null, values);
    db.close();
}
public Event_Data findevent(String eventname)
{
    String query = "Select * FROM " + TABLE_EVENTS + " WHERE " +     COLUMN_EVENTNAME + " =  \"" + eventname + "\"";

    SQLiteDatabase db = this.getWritableDatabase();

    Cursor cursor = db.rawQuery(query, null);

    Event_Data event = new Event_Data();

    if (cursor.moveToFirst()) {
        cursor.moveToFirst();
        event.setID(Integer.parseInt(cursor.getString(0)));
        event.setEventName(cursor.getString(1));
        event.setType(cursor.getString(2));
        event.setQuantity(cursor.getString(3));
        event.setPrice(cursor.getString(4));
        event.setDate(cursor.getString(5));
        event.setTim(cursor.getString(6));
        cursor.close();
    } else {
        event = null;
    }
    db.close();
    return event;
}
public boolean deleteevent(String eventname)
{
    boolean result = false;

    String query = "Select * FROM " + TABLE_EVENTS + " WHERE " +     COLUMN_EVENTNAME + " =  \"" + eventname + "\"";

    SQLiteDatabase db = this.getWritableDatabase();

    Cursor cursor = db.rawQuery(query, null);

    Event_Data event = new Event_Data();

    if (cursor.moveToFirst()) {
        event.setID(Integer.parseInt(cursor.getString(0)));
        db.delete(TABLE_EVENTS, COLUMN_ID + " = ?",
                new String[] { String.valueOf(event.getID()) });
        cursor.close();
        result = true;
    }
    db.close();
    return result;
}
}


enter code here



public class Event_Data {
private int id;
private String name;
private String type;
private String price;
private String qunt;
private String dat;
private String tim;
public Event_Data() {

}

public Event_Data(int vid, String vname, String vtype, String vprice,     String vqunat, String vdat, String vtim) {

    this.id = vid;
    this.name=vname;
    this.type=vtype;
    this.price=vprice;
    this.qunt=vqunat;
    this.dat=vdat;
    this.tim=vtim;
}

public Event_Data(String vname, String vtype, String vprice, String      vqunat, String vdat, String vtim) {
    this.name=vname;
    this.type=vtype;
    this.price=vprice;
    this.qunt=vqunat;
    this.dat=vdat;
    this.tim=vtim;
}

public void setID(int vid) {
    this.id = vid;
}

public int getID() {
    return this.id;
}

public void setEventName(String vname) {
    this.name = vname;
}

public String getEventName() {
    return this.name;
}

public void setQuantity(String vquant) {
    this.qunt = vquant;
}

public String getQuantity() {
    return this.qunt;
}
public void setType(String vtype)
{
    this.type= vtype;
}
public String getType()
{
    return this.type;
}
public void setPrice(String vprice)
{
    this.price= vprice;
}
public String getPrice()
{
    return this.price;
}
public void setDate(String vdate)
{
    this.dat= vdate;
}
public String getDate()
{
    return this.dat;
}
public void setTim(String vtime)
{
    this.tim = vtime;
}
public String getTim()
{
    return this.tim;
}
}

Answer 1

String query = "Select * FROM " + TABLE_EVENTS + " WHERE " +     COLUMN_EVENTNAME + " =  \"" + eventname + "\"";

因为你使用双引号而不是使用单引号作为

 String query = "Select * FROM " + TABLE_EVENTS + " WHERE " +     COLUMN_EVENTNAME + " ='" + eventname + "'";

或使用android在SqliteDatabase类中具有的查询方法

db.query(TABLE_EVENTS ,null,COLUMN_EVENTNAME + " =?",new String[]{eventname },null,null,null);

if (cursor.getCount()>0&&cursor.moveToFirst()) {

        event.setID(Integer.parseInt(cursor.getString(cursor.getColumnIndex(COLUMN_ID)));
        event.setEventName(cursor.getString(cursor.getColumnIndex(COLUMN_EVENTNAME)));
        event.setType(cursor.getString(cursor.getColumnIndex(COLUMN_TYPE )));
        event.setQuantity(cursor.getString(cursor.getColumnIndex(COLUMN_QUANTITY)));
        event.setPrice(cursor.getString(cursor.getColumnIndex(COLUMN_PRICE)));
        event.setDate(cursor.getString(cursor.getColumnIndex(COLUMN_DATE )));
        event.setTim(cursor.getString(cursor.getColumnIndex(COLUMN_TIME )));
        cursor.close();
    }

想从android中检索数据库中的所有数据

1 个答案: