How to add default time to a field in MySQL

Date type differences and uses

MySQL has five date types: date, time, year, datetime, and timestamp.

Application scenarios:

• In the data table, to record when each piece of data was created, the application does not need to record it specifically, but the data database obtains the current time and automatically records the creation time;
• In the database, to record when each piece of data was modified, the application does not need to record it specifically, but the data database obtains the current time and automatically records the modification time;

Implementation:

• Set the field type to TIMESTAMP
• Set the default value to CURRENT_TIMESTAMP

Example application:

MySQL script implementation use case

`create_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT 'Creation time',
`update_time` datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT 'Update time',
`datalevel` tinyint(1) DEFAULT '1' COMMENT 'Has it been deleted (0 deleted/1 normal)',

ALTER TABLE table_name
ADD COLUMN create_time datetime NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'Creation time';
ALTER TABLE table_name
ADD COLUMN update_time datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT 'Update time';
ALTER TABLE table_name
ADD COLUMN datalevel tinyint(1) DEFAULT '1' COMMENT 'Has it been deleted (0 deleted/1 normal)';

MySQL creates a normal index

ALTER TABLE projectfile ADD INDEX (fileuploadercode, projectid);

Summarize

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