什么是升级sqllite分贝的正确方法？ [英] what is the correct way to upgrade sqllite db?

问题描述

private static final String TABLE_MAIN_CREATE = "CREATE TABLE IF NOT EXISTS " + TABLE_MAIN_NAME + " ( a INTEGER, b LONG, c TEXT, d TEXT, e DATETIME, f TEXT)";
private static final String TABLE_MAIN_UPGRADE = "ALTER TABLE " + TABLE_MAIN_NAME + " ADD Column f TEXT";

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

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if (oldVersion < newVersion) {
        db.execSQL(TABLE_MAIN_UPGRADE);
    }
    onCreate(db);
}

在previous数据库的版本是不带F字段中。 这是升级数据库的正确方法？ 难道我在onUpgrade需要的onCreate（DB）？

The previous db version was without the "f" field. Is this the correct way to upgrade the DB? Do I need onCreate(db) in onUpgrade?

我这样做了几次，每次都让我有另外一个例外： 1）表已经存在，所以我说IF NOT EXISTS 2）看不懂行0，第5栏的错误在这里我失去了它......

I did this several times and each time I got another exception: 1) table already exists so I added "IF NOT EXISTS" 2) could not read row 0, col 5 error here I lost it....

这是升级数据库的正确方法？

IS this the correct way to upgrade the db?

我要保持我的数据

推荐答案

您需要做的事情取决于 oldVersion ...

you have to do something depends on oldVersion ...

FX：你可以分贝版本从10-14，上了年纪那么10你不瓦纳的支持，并在每个新版本中添加新列code应该看起来像（动态网页为14）：

fx: you can have db versions from 10-14, the older then 10 you dont wana support and at every new version you add a new column the code should looks like(newVersion is 14):

private static final String TABLE_MAIN_CREATE_14 = 
    "CREATE TABLE IF NOT EXISTS " + TABLE_MAIN_NAME + 
    " ( a INTEGER, b LONG, c TEXT, d TEXT, e DATETIME, f TEXT, g TEXT, h TEXT, i TEXT)";
private static final String TABLE_MAIN_UPGRADE_10_11 = 
    "ALTER TABLE " + TABLE_MAIN_NAME + " ADD Column f TEXT";
private static final String TABLE_MAIN_UPGRADE_11_12 = 
    "ALTER TABLE " + TABLE_MAIN_NAME + " ADD Column g TEXT";
private static final String TABLE_MAIN_UPGRADE_12_13 = 
    "ALTER TABLE " + TABLE_MAIN_NAME + " ADD Column h TEXT";
private static final String TABLE_MAIN_UPGRADE_13_14 = 
    "ALTER TABLE " + TABLE_MAIN_NAME + " ADD Column i TEXT";
    @Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(TABLE_MAIN_CREATE_14);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    switch(oldVersion){
            case 10: // from 10 to 11 and go to next case
                db.execSQL(TABLE_MAIN_UPGRADE_10_11);
            case 11: // from 11 to 12 and go to next case
                db.execSQL(TABLE_MAIN_UPGRADE_11_12);
            case 12: // from 12 to 13 and go to next case
                db.execSQL(TABLE_MAIN_UPGRADE_12_13);
            case 13: // from 13 to newVersion
                db.execSQL(TABLE_MAIN_UPGRADE_13_14);
                break;
            default:
                //not upgratable too old - so we should drop and recreate;
                db.execSQL("DROP TABLE IF EXISTS " + TABLE_MAIN_NAME  );
                onCreate(db);
                break;
    }
}

编辑：嗯，好像有人有他个人的事情，我和downvoting这个答案，那么成熟：）

edit: hmmm, seems like someone has something personal to me and downvoting this answer, so mature :)

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