Update SQL with consecutive numbering

Question

I want to update a table with consecutive numbering starting with 1. The update has a where clause so only results that meet the clause will be renumbered. Can I accomplish

Answer 1

As well as using a CTE or a WITH, it is also possible to use an update with a self-join to the same table:

UPDATE a
SET a.columnToBeSet = b.sequence
FROM tableXxx a
INNER JOIN
(
   SELECT ROW_NUMBER() OVER ( ORDER BY columnX ) AS sequence, columnY, columnZ
   FROM tableXxx
   WHERE columnY = @groupId AND columnY = @lang2
) b ON b.columnY = a.columnY AND b.columnZ = a.columnZ

The derived table, alias b, is used to generated the sequence via the ROW_NUMBER() function together with some other columns which form a virtual primary key. Typically, each row will require a unique sequence value.

The WHERE clause is optional and limits the update to those rows that satisfy the specified conditions.

The derived table is then joined to the same table, alias a, joining on the virtual primary key columns with the column to be updated set to the generated sequence.