Question

I need to negate the value of a column for all the rows in a column. I am trying to do so using the following query, but it is not updating any Row:

sqliteDatabase.rawQuery("UPDATE "+ SQL_TABLE_NAME + " SET "+ COL_1 +" = " + "-"+COL_1  , null);

Where COL-1 = col_1, which is of type integer in the table.

–Twinks

Answer 1

You could Multiply the column by -1

 Update SQL_TABLE_NAME Set COL_1 = COL_1 * -1

Mind you saying that, your query format works for me;

 Update tPerson Set Age = -Age

If I were you I’d create a string and set your query to that so you can check it’s being set as you expect:

 String sql = "UPDATE "+ SQL_TABLE_NAME + " SET "+ COL_1 +" = " + "-" + COL_1;
 sqliteDatabase.rawQuery(sql, null); //breakpoint here, and check sql var

Does your SQL_TABLE_NAME have a space in it? Try wrapping it in square brackets, and perhaps the same with your column name.

Edit:

I would recommend updating primary keys to be negative, but to accomplish this you could do something like this:

 SET IDENTITY_INSERT Person ON

 Insert Into Person ([Id], [Name], [Age])
 Select -[Id], [Name], [Age] From Person

 SET IDENTITY_INSERT Person OFF

(but this will duplicate your table, you might want to shove the data into a temp table) – however I think this is a horrible solution. I’d try and find a way to restructure your table schema so it isn’t the primary key.