php - mysql error 1064 when changing structure of date from datetime to VARCHAR -

there issue when try change structure of 1 of table in mysql user db table , has many fields , 1 of them register date field

it set datetime , trying change varchar using phpmyadmin best way know using limited mysql / phpmyadmin expertise.

alter table  abnhd_user change  registerdate  registerdate varchar not null default '0000-00-00 00:00:00' 

when try change datetime varchar, following error

#1064 - have error in sql syntax; check manual corresponds mysql server version right syntax use near 'not null default '0000-00-00 00:00:00'' @ line 1

you executed query

alter table  abnhd_user change  registerdate  registerdate varchar not null default '0000-00-00 00:00:00' 

but mysql doesn't have default value '0000-00-00 00:00:00' varchar use below sql change varchar

alter table abnhd_user modify registerdate varchar(30);