unexpected additional columns

Question

in most of my tables, command

SELECT column_name FROM information_schema.columns WHERE table_name='table'

worked as expected, but in one table i am getting additional tables that i was not expecting. What are those and how can i not see them ?

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.12    |
+-----------+

mysql> DESCRIBE users;
+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| userID      | int(11)      | NO   | PRI | NULL    | auto_increment |
| username    | varchar(20)  | YES  |     | NULL    |                |
| password    | varchar(100) | YES  |     | NULL    |                |
| email       | varchar(50)  | YES  |     | NULL    |                |
| avatar      | varchar(255) | YES  |     | NULL    |                |
| admin       | tinyint(1)   | YES  |     | NULL    |                |
| createdTime | datetime     | YES  |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

mysql> SELECT column_name FROM information_schema.columns WHERE table_name='users' ORDER BY ORDINAL_POSITION;
+---------------------+
| COLUMN_NAME         |
+---------------------+
| userID              |
| USER                |
| CURRENT_CONNECTIONS |
| username            |
| password            |
| TOTAL_CONNECTIONS   |
| email               |
| avatar              |
| admin               |
| createdTime         |
+---------------------+
10 rows in set (0.01 sec)

As you can see, I am getting 3 additional columns "USER, CURRENT_CONNECTIONS, TOTAL_CONNECTIONS" which i was not expecting. I need just column names as they are so that i can pass those columns to python for parsing

Is maybe name 'users' clashing with some internal Mysql column or other database?

Answer 1

Like @ypercubeᵀᴹ noticed and suggested:

SELECT column_name 
FROM information_schema.columns 
WHERE table_schema = 'mydatabase' 
  AND table_name='users';

does the trick

Answer 2

This is fairly common to have happen.

I believe you see these because you have permissions (read) on these as well.

as far as

What are those and how can i not see them ?

These are system schemas.

Breakdown

If your not a

1. DBA
2. Concerned about performance, security or maintenance
3. Where your custom snippets live.

They probably will be a waste of your time.

Either way if you do SQL I would urge you to read up on them, as there can be many beneficial items in there.

• System Schema
• MySQL Schema
• Information Schema
• .mysqlworkbench Schema
• Performance Schema

SELECT column_name
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 
                           'information_schema', 
                           '.mysqlworkbench', 
                           'performance_schema');

This works for tables as well.

SELECT table_name
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_SCHEMA NOT IN ('sys', 'mysql',
                           'information_schema',
                           '.mysqlworkbench',
                           'performance_schema');