在Android中迁移会议室数据库

Question

I just updated my database in android and can't get an app to migrate.

The change I made is that I added ( autoGenerate = true ) to my @PrimaryKey

@PrimaryKey(autoGenerate = true)
private int id;

I tried a whole lot of things, but I cannot get the migration to work.

The problem arises in my AppDatabase class where i inserted following code:

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE inventory");
    }
};

The ALTER TABLE inventory isn't the right command but I cannot figure out what is

Answer 1

The SQL statement is incorrect ALTER TABLE inventory . You did not specify what is going to be changed on the table.

For example: ALTER TABLE inventory ADD name TEXT that means there is a new column name in type TEXT to be added in the table inventory .

While your case is a constraint change, and there is no way to alter constraint. But you can drop the constraint and add it again.

Please read the answer here: How to Alter Constraint