[Bug]: Editing a column using table default Collation then hard sets that collation for the column #20411

Describe the bug

If a column does not have a column level collation set the column will follow the table collation.

However when you 'change' a column that has no collation set the collation drop down will automatically select the option with the value of the table collation (rather than the first blank option). when saving the changes this extends the definition of this column to include the collation... this change may be undesired as not intentionally requested.

Although this maybe considered to be making a change that doesn't really change anything it does impact on dumps / migrations and table structure audits

How to Reproduce

0 - preview current structure using mysqldump -u -p {$schema_name} {$table_name}
1 - Go to the structure of any table containing a text / varchar / enum / etc column (that does not have a collation defined for the column)
2 - Select 'change' against that column
3 - make a change to a property other than collate (e.g. toggle Null / Not Null)
4 - hit save
5 - review new structure using mysqldump -u -p {$schema_name} {$table_name}

Expected behavior

0 - preview current structure using mysqldump -u -p {$schema_name} {$table_name}
1 - Go to the structure of any table containing a text / varchar / enum / etc column (that does not have a collation defined for the column)
2 - Select 'change' against that column
3 - make a change to a property other than collate (e.g. toggle Null / Not Null)
4 - hit save
5 - review new structure using mysqldump -u -p {$schema_name} {$table_name}

only the change made is different between (0) and (5) not a change to the column collate definition

Screenshots

No response

Operating System

Linux

Web Server

No response

Database Server

MySQL

Database version

8.4.10-0ubuntu0.26.04.1

PHP version

8.5.4

phpMyAdmin version

5.2.3

browser

FireFox 153

Additional context

This bug is not a million miles to the default value set to empty string bug - so may have a similar fix [https://github.com//issues/20409 ]