Mysql: Unable to drop a columns NULL default
I suspect your integrator was asking to remove the NULL from the column.

First check there are no NULL columns:

SELECT * FROM TableName WHERE Prenom IS NULL


Or to set to empty string:

UPDATE TableName SET Prenom = "" WHERE Prenom IS NULL


Then NULL for the column can removed with:




select version();



| version()                                   |
| :------------------------------------------ |
| 10.3.11-MariaDB-1:10.3.11+maria~stretch-log |






create table TableName ( Prenom  varchar(50) )



✓






show create table TableName



Table     | Create Table                                                                                               
:-------- | :----------------------------------------------------------------------------------------------------------
TableName | CREATE TABLE `TableName` (`Prenom` varchar(50) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=latin1






ALTER TABLE TableName MODIFY COLUMN Prenom varchar(50) NOT NULL



✓






show create table TableName



Table     | Create Table                                                                                           
:-------- | :------------------------------------------------------------------------------------------------------
TableName | CREATE TABLE `TableName` (`Prenom` varchar(50) NOT NULL) ENGINE=InnoDB DEFAULT CHARSET=latin1



db&lt;>fiddle here