Question

我的数据库中有五个表我想再将两个colomns添加到一个表中我怎么能提前帮助我。这是我的表格

                   sqLiteDatabase.execSQL(CREATE_ProductSales_TABLE);
                 sqLiteDatabase.execSQL(CREATE_UNIT_TABLE);
                  sqLiteDatabase.execSQL(CREATE_STOCK_TABLE);
                 sqLiteDatabase.execSQL(CREATE_OrderSales_TABLE);(i want to add two coloms to this table)
                sqLiteDatabase.execSQL(CREATE_Prod_TABLE);
                 sqLiteDatabase.execSQL(CREATE_CAT_TABLE);

如何执行onupgrade方法我应该写什么来更新android中的表和非更新表

Answer 1

创建表后，您可以使用alter语句添加

等列

ALTER TABLE {OrderSales_Table} ADD COLUMN ColumnName {Integer};

Answer 2

使用我用来创建表格的SQLiteOpenHelper类。

看看我的班级

public class DBHelper extends SQLiteOpenHelper {

// Database Information
public static final String DB_NAME = "ROADTRIP_DB";

// database version
static final int DB_VERSION = 1;

//<editor-fold desc = "TABLE NAMES">
public static final String DETAILS = "details";
//</editor-fold>

//<editor-fold desc="TABLE DETAILS">
public static final String ID = "_id";
public static final String NAME = "name";
public static final String EMAIL = "email";
public static final String MOBILE = "mobile";
public static final String DATETIMESTAMP = "datetimestamp";
public static final String STATUS = "status";
//</editor-fold>


//<editor-fold desc="CREATE_ROADTRIP_TABLE">
private static final String CREATE_ROADTRIP_TABLE = "CREATE TABLE IF NOT EXISTS " + DETAILS + "("
        + ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
        + NAME + " VARCHAR,"
        + EMAIL + " VARCHAR,"
        + MOBILE + " VARCHAR,"
        + DATETIMESTAMP + " DATETIME,"
        + STATUS + " INTEGER)";
//</editor-fold>


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

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

@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
    onCreate(db);
    }
}

我还使用另一个类在我的数据库上添加命令

public class DBManager {

private DBHelper DBHelper;

private Context context;

private SQLiteDatabase database;

public DBManager(Context c) {
    context = c;
}

public DBManager open() throws SQLException {
    DBHelper = new DBHelper(context);
    database = DBHelper.getWritableDatabase();
    return this;
}

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

//inserting data to database
//<editor-fold desc = "insertToDetails">
public void insertToDetails(String name,
                                  String email,
                                  String mobile,
                                  String datetimestamp,
                                  String status) {

    ContentValues contentValue = new ContentValues();
    contentValue.put(DBHelper.NAME, name);
    contentValue.put(DBHelper.EMAIL, email);
    contentValue.put(DBHelper.MOBILE, mobile);
    contentValue.put(DBHelper.DATETIMESTAMP, datetimestamp);
    contentValue.put(DBHelper.STATUS, status);

    database.insert(DETAILS, null, contentValue);
}
//</editor-fold>

//for getting the data from database fuction
public Cursor fetchData() {
    String[] columns = new String[]{
            DBHelper.ID,
            DBHelper.NAME,
            DBHelper.EMAIL,
            DBHelper.MOBILE
    };
    Cursor cursor = database.query(DETAILS, columns, null, null, null, null, null);
    if (cursor != null) {
        cursor.moveToFirst();
    }
    return cursor;
}

}

当我想向我的database添加数据时。我打电话

   dbManager.insertToDetails("column1","column2"...);

花点时间阅读本文。这真的让你的生活更加轻松database

修改

在使用之前，请确保必须声明：

SQLiteDatabase sqldb; DBHelper dbHelper; DBManager dbManager;

并在您希望使用数据库防止数据库泄漏时，在onCreate（for extends AppCompactActivity）或onCreateView（Fragment）上调用此方法。希望这有帮助

dbHelper = new DBHelper(getContext()); sqldb = dbHelper.getReadableDatabase(); dbManager = new DBManager(getActivity()); dbManager.open();

Answer 3

您可以使用alter语句添加新列，如

sqLiteDatabase.execSQL（“ALTER TABLE Tablename ADD COLUMN Newcolumn VARCHAR DEFAULT 0”）;

我想在数据库中添加两个新的colomns，我该怎么办？

3 个答案: