How do I delete column from table in room database?

Question

How do I delete column from table in room database android.I alredy try all the way drop and delete not working.

This code also not working:-

static final Migration MIGRATION_3_4 = new Migration(3, 4) 

{
    @Override
    public void migrate(SupportSQLiteDatabase database) 
{

 database.execSQL("CREATE TABLE users_new (userid TEXT, username TEXT, last_update INTEGER, PRIMARY KEY(userid))");

// Copy the data

 database.execSQL("INSERT INTO users_new (userid, username, last_update) SELECT userid, username, last_update FROM users");

// Remove the old table
 database.execSQL("DROP TABLE users");

// Change the table name to the correct one

 database.execSQL("ALTER TABLE users_new RENAME TO users");

    }
};

so you are migrating from a starting version, which has a column that the new version does not have, right? how do you know those SQL commands are not working? — Gregorio Palamà, Sep 06 '18 at 10:51
When I am runinng code it give error in this code database.execSQL("ALTER TABLE users DROP COLUMN users_id"); and the code i mention with queation is also not working .And you right about so you are migrating from a starting version, which has a column that the new version does not have, right. — Avadhesh Mourya, Sep 06 '18 at 11:00

score 1 · Answer 1 · answered Oct 05 '18 at 16:38

Android ROOM is based on SQL Lite which does not allow dropping database table columns. Instead you have to:

create a temporary table without the column you are trying to delete,
copy all records from old table to new table,
drop the old table,
rename new table to same name as old table

See related question:Sqlite Dropping Column from table

How do I delete column from table in room database?

1 Answers1