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What is default timestamp in MySQL?
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TIMESTAMP has a default of 0 unless defined with the NULL attribute, in which case the default is NULL .
How set MySQL default NOT NULL?
If you need to set a MySQL column to not accept null values, then you can add NOT NULL constraint in MySQL. You can add NOT NULL constraint when you create table table using CREATE TABLE statement, or add NOT NULL constraint in existing table using ALTER TABLE statement.
What is default NULL in MySQL?
If a data type specification includes no explicit DEFAULT value, MySQL determines the default value as follows: If the column can take NULL as a value, the column is defined with an explicit DEFAULT NULL clause. If the column cannot take NULL as a value, MySQL defines the column with no explicit DEFAULT clause.
What is NULL and not null in MySQL?
NOT NULL means that the column can not have a NULL value for any record; NULL means NULL is an allowable value (even when the column has a foreign key constraint). Generally you want as many columns as possible to be NOT NULL because you want to be sure data is always there.
When is a timestamp ( auto ) updated in MySQL?
An auto-updated column is automatically updated to the current timestamp when the value of any other column in the row is changed from its current value. An auto-updated column remains unchanged if all other columns are set to their current values.
How does MySQL work with timestamp columns?
This works with TIMESTAMP and DATETIME columns. (Prior to MySQL version 5.6.5 it only worked with TIMESTAMP s) When you use TIMESTAMP s, 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.
What happens to the auto updated column in MySQL?
An auto-updated column remains unchanged if all other columns are set to their current values. it will not change the value of updated_at, since price value wasn’t actually changed (it was already 2).