If I have a column in a table of type
If the column is auto-updated, it is automatically updated to the
current timestamp when the value of any other column in the row is
changed from its current value. The column remains unchanged if all
other columns are set to their current values. To prevent the column
from updating when other columns change, explicitly set it to its
current value. To update the column even when other columns do not
change, explicitly set it to the value it should have]2
Give the command
SHOW CREATE TABLE whatever
Then look at the table definition.
It probably has a line like this
logtime TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
DEFAULT CURRENT_TIMESTAMP means that any
INSERT without an explicit time stamp setting uses the current time. Likewise,
ON UPDATE CURRENT_TIMESTAMP means that any update without an explicit timestamp results in an update to the current timestamp value.
You can control this default behavior when creating your table.
Or, if the timestamp column wasn't created correctly in the first place, you can change it.
ALTER TABLE whatevertable CHANGE whatevercolumn whatevercolumn TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP;
This will cause both INSERT and UPDATE operations on the table automatically to update your timestamp column. If you want to update
whatevertable without changing the timestamp, that is,
To prevent the column from updating when other columns change
then you need to issue this kind of update.
UPDATE whatevertable SET something = 'newvalue', whatevercolumn = whatevercolumn WHERE someindex = 'indexvalue'
And, this works with
TIMESTAMP columns only, not
DATE columns. Because the columns are
TIMESTAMPs, time zones are accounted for: on a correctly configured server machine, those values are always stored in UTC and translated to local time upon retrieval.