how to set default value for text type in mysql

Question

CREATE TABLE IF NOT EXISTS `te` (
  `id` int(30) NOT NULL,
  `name` text NOT NULL,
  `address` text NOT NULL,
  `Aboutus` text NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Here Table 'te' consist 4 fields id, name, address, Aboutus, Aboutus is optional means how can i update default text to the Profile in db , by phpmyadmin sql

Answer 1

I have changed not null to null for about us field

CREATE TABLE IF NOT EXISTS `te` (
  `id` int(30) NOT NULL,
  `name` text NOT NULL,
  `address` text NOT NULL,
  `Aboutus` text NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Here is your trigger BEFORE INSERT

CREATE TRIGGER new_insert
BEFORE INSERT ON `te`
FOR EACH ROW 
SET NEW.`Aboutus` = CASE WHEN NEW.Aboutus IS NULL THEN 'Not Updated' ELSE NEW.Aboutus END
;

Insert without Aboutus

INSERT INTO `te` (`id`, `name`, `address`) 
VALUES (1, 'name', 'address') ;

Insert with Aboutus

INSERT INTO `te` (`id`, `name`, `address`, `Aboutus`) 
VALUES (2, 'name', 'address', 'Aboutus') ;

Insert by passing null Aboutus

INSERT INTO `te` (`id`, `name`, `address`, `Aboutus`) 
VALUES (3, 'name', 'address', null) ;

Demo

Edit As @garethD pointed a case for update scenario,you also need another trigger on BEFORE UPDATE so if null appears in update then aboutus should be updated as Not Updated

CREATE TRIGGER update_trigger
BEFORE UPDATE ON `te`
FOR EACH ROW 
SET NEW.`Aboutus` = CASE WHEN NEW.Aboutus IS NULL THEN 'Not Updated' ELSE NEW.Aboutus END
;

UPDATE te
SET AboutUs = NULL;

Demo 2