How to update an SQLite Database and NOT lose all existing data?

Question

I\'m adding a table to my app\'s SQLite DB. All my syntax there is fine, not the issue. But I\'m having some trouble getting the new table to be created properly. I added the ne

Answer 1

if DB version : 6

Ex : There is a table with 5 columns

When you upgrade to : 7 ( I am adding 1 new column in the 3 tables)

 1. We need to add the columns when creating a table

 2. onUpgrade method:

 if (oldVersion < 7) 
 { 
    db.execSQL(DATABASE_ALTER_ADD_PAPER_PAID);
    db.execSQL(DATABASE_ALTER_LAST_UPLOADED);
    db.execSQL(DATABASE_ALTER_PAPER_LABEL); 
 }

Where : "DATABASE_ALTER_ADD_PAPER_PAID" is query.

EX: public static final String DATABASE_ALTER_ADD_PAPER_PAID = "ALTER TABLE "
                + TableConstants.MY_PAPERS_TABLE + " ADD COLUMN " + COLUMN_PAPER_PAID + " TEXT;";

After above two operation it will works fine for the fresh install user and app upgrade user

Answer 2

You can do anything you want in onUpgrade. You can use ALTER to add new columns to your table.

Worst case, if your schema is completely and entirely different, you'll have to create the new table, populate it using data from the old table, and then delete the old table.

In any case, onUpgrade was designed to allow for a smooth upgrade without any loss of data. It's just up to you to implement it properly.