Question

android中的SQLite在创建数据库、创建表后，如何给表增加列数，或者更新版本？

如题，代码如下：
private SQLiteDatabase db;
db = (new DatabaseHelper(S2iCamera.this,"mytable",null,1)).getWritableDatabase();
db.execSQL("CREATE TABLE if not exists saveS2i (_id INTEGER PRIMARY KEY AUTOINCREMENT, path TEXT, date TEXT, dateFormat TEXT);");
db.close();
在创建了表mytable以后，我需要修改程序，更新数据库版本，以新增列数，比方说这样：
private SQLiteDatabase db;
db = (new DatabaseHelper(S2iCamera.this,"mytable",null,1)).getWritableDatabase();
db.execSQL("CREATE TABLE if not exists saveS2i (_id INTEGER PRIMARY KEY AUTOINCREMENT, new TEXT, path TEXT, date TEXT, dateFormat TEXT);");
db.close();
新增加了new列，但是更新后数据库里的mytable表并没有增加new列，请问如何能给已经发布的程序增加列数？

若以下回答无法解决问题，邀请你更新回答

Answer 1

//定义升级函数
private void upgradeDatabaseToVersion1(SQLiteDatabase db) {
// Add 'new' column to mytable table.
db.execSQL("ALTER TABLE mytable ADD COLUMN new TEXT");
}

//重写onUpgrade
public void onUpgrade(SQLiteDatabase db, int oldVersion, int currentVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to " + currentVersion + ".");

switch (oldVersion) {
case 0:
if (currentVersion <= 1) {
return;
}

db.beginTransaction();
try {
upgradeDatabaseToVersion1(db);
db.setTransactionSuccessful();
} catch (Throwable ex) {
Log.e(TAG, ex.getMessage(), ex);
break;
} finally {
db.endTransaction();
}

return;
}

Log.e(TAG, "Destroying all old data.");
dropAll(db);
onCreate(db);
}

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