Equivalent to Table.TransformColumns that allows expressions that reference other columns

Power Query desperately needs the ability to modify a column's values using other columns on the record as part of the update expression. This could be easily achieved by allowing the '_' operator to refer to the record (which it does in pretty much every other case), rather than the cell value.

At present, if you want to change a cell's value at all using a value from another column, you have to create a new column, drop the old column, then rename the new column to the old column's name. When trying to do something over multiple columns this leads to very bad bloated code.

In SQL, it's absolutely trivial to do this: UPDATE SomeTable SET SomeColumn = SomeOtherColumn [+ whatever else I want to do]

Power Query is not an acceptable enterprise ETL tool until it can get the basics right

Plus it would be helpful if someone could fix these forums so they stop stripping the whitespace out of posts and declaring any use of the code formatting feature as malicious. As usual, half-finished, barely usable products from Microsoft