Underscore in field name structure change

[ChrisHSandN]

Describe the bug

Attempting to change the structure of a field containing an _ can incorrectly match the wrong field.

To Reproduce

Steps to reproduce the behavior:

1. Create a table with fields aid and _id

CREATE TABLE `test` (
 `aid` tinyint(4) NOT NULL,
 `_id` tinyint(4) NOT NULL,
 PRIMARY KEY (`aid`)
) ENGINE=InnoDB 

2. Click on Structure
3. Click Change on the field _id
4. aid field is edited

Expected behavior

_id field should be edited

Screenshots

Server configuration

• Operating system:
• Web server: CentOS 7
• Database version: MariaDB 10.4.11
• PHP version: 7.3.14
• phpMyAdmin version: 5.0.1

Client configuration

• Browser: Chrome Latest
• Operating system: Windows 10

[williamdes]

Thank you @ChrisHSandN for the report !
I also reproduced this issue on 5.1.0-dev.

[williamdes]

I found the issue 🎉
And you found the perfect test case 👍

-- says I have a unknown char at first position
SHOW FULL COLUMNS FROM `test` LIKE '_id'
-- says I have the `_` char at the first position
SHOW FULL COLUMNS FROM `test` LIKE '\_id'

To reproduce, have a column named what you want, then create another one containing a _ at least once at start.
Then be sure to have the column having a _ last.

[williamdes]

I added tests in 0a1d09b and fixed it in 8917e77
Next 5.1.0 release will contain this fix.