184.108.40.206 UPDATE Differences
If you access a column from the table to be updated in an expression,
UPDATE uses the current value of the column. The second assignment in the following statement sets
col2 to the current (updated)
col1 value, not the original
col1 value. The result is that
col2 have the same value. This behavior differs from standard SQL.
UPDATE t1 SET col1 = col1 + 1, col2 = col1;