我想向数据库添加两个新列，我该怎么做？ [复制]答案

【问题标题】：i want to add two new colomns to database how can i? [duplicate]我想向数据库添加两个新列，我该怎么做？ [复制]
【发布时间】：2018-06-01 11:44:39
【问题描述】：

我的数据库中有五个表我想在一个表中再添加两个列我该如何帮助我提前谢谢。这是我的桌子

                   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方法在android中更新表和不更新表我应该写什么

【问题讨论】：

什么是CREATE_OrderSales_TABLE？我presume 它是一个字符串，但它的值是多少？你如何设置它的值？

标签： android sql android-sqlite android-sql

【解决方案1】：

创建表后，您可以使用alter语句添加列，例如

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

【讨论】：

【解决方案2】：

您可以使用 alter 语句添加新列，如 as

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

【讨论】：

【解决方案3】：

使用我用来创建表的SQLiteOpenHelper 类。

看看我的课

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中添加命令

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。我只是打电话

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

花点时间阅读这篇文章。 database 真的让你的生活更轻松

编辑

在你可以使用它之前，确保你必须声明这个：

SQLiteDatabase sqldb;
DBHelper dbHelper;
DBManager dbManager;

只要您想使用数据库来防止数据库泄漏，请在您的 onCreate (for extends AppCompactActivity) 或 onCreateView（对于 Fragment）上调用此函数。希望这会有所帮助

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

【讨论】：