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Is it more efficient to execute one UPDATE statement with multiple columns
UPDATE myTable
SET [col1] = [col1] + 1,
[col2] = [col2] + 1,
[col3] = [col3] + 1,
...
[colN] = [colN] + 1
or multiple UPDATE statements with a single column each?
UPDATE myTable SET [col1] = [col1] + 1
UPDATE myTable SET [col2] = [col2] + 1
UPDATE myTable SET [col3] = [col3] + 1
...
UPDATE myTable SET [colN] = [colN] + 1
This may vary with the particular implementation of any one database engine, but I’m going to cast my vote that a single update will generally be better performing than successive updates. The DB need only find the desired record once, update the relevant values, and be done with it.
Now, given that there are plan caches, indexes, optimizers, and other elements at hand to make things smarter on the fly, it may well be that the multi-update version will nearly approach the performance of the former, but my expectation is that, even under the best of circumstances, the former will perform better.