MySQL timestamp type field current_timestamp with on UPDATE Current_timestamp property

TIMESTAMP has two properties, namely Current_timestamp and on UPDATE Current_timestamp two, respectively, the following are used:

1.current_timestamp

When you want to perform an insert operation to the database, if you have a timestamp field property set to

Current_timestamp, the current system time is inserted regardless of whether the field has a wooden set value.

2.ON UPDATE Current_timestamp

When the update operation is performed, and the field has the on Update Current_timestamp property. The value of the field is updated to the time of the current update operation, regardless of whether the value has changed.

Variants of the timestamp

1.TIMESTAMP DEFAULT current_timestamp on UPDATE current_timestamp

Refreshes the data column when new records are created and existing records are modified

2.TIMESTAMP DEFAULT Current_timestamp

This field is set to the current time when a new record is created, but it is not refreshed when you modify it later

3.TIMESTAMP on UPDATE Current_timestamp

Set this field to 0 when creating a new record, and refresh it later when you modify it

4.TIMESTAMP DEFAULT ' Yyyy-mm-dd hh:mm:ss ' on UPDATE current_timestamp

Set this field to the given value when you create a new record, and refresh it later when you modify it

Use triggers to override:

CREATE TABLE' Example ' (' ID ')INTEGERUNSIGNED not NULLauto_increment, ' created 'TIMESTAMP  not NULL DEFAULT Current_timestamp, ' lastupdated 'DATETIME  not NULL,  PRIMARY KEY(' id ')) ENGINE=InnoDB;DROP TRIGGER IF EXISTS' Update_example_trigger ';D elimiter//CREATE TRIGGER' Update_example_trigger ' beforeUPDATE  on' Example ' forEach ROWSETNEW ' lastupdated '=Now ()//DELIMITER;

MySQL timestamp type field current_timestamp and on UPDATE current_timestamp properties