Search Conditions for UPDATE Statements
If you use UPDATE statements, the following restrictions apply to the use of
search conditions.If the new value of a column is calculated in an arithmetical expression, an inversion of this column, that is, the corresponding index, cannot be used during the search.
UPDATE <table_name> SET columnx = columnx + 3 WHERE columnx IN (100, 103, 106, 109, 112)
This SQL statement can lead to erroneous results, if the inversion lists were gradually processed with the values 100, 103, 106, 109, and 112.
You should also consider this factor when using FOR UPDATE in the SELECT statement.