How to understand the virtual column of mysql 5.7rowid

How to understand the virtual column of mysql 5.7A _ rowid. For this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

Check the official material 13 SQL Statement Syntax13.1 Data Definition Statements13.1.14 CREATE INDEX Syntax test examples

Create a test table and insert data

Mysql > create table t_rowid (an int,b int,key (a)); Query OK, 0 rows affected (0.03 sec) mysql > insert into t_rowid select 1 OK 1 row affected (0.00 sec) Records: 1 Duplicates: 0 Warnings: 0mysql > insert into t_rowid select 2 * * query OK, 1 row affected (0.00 sec) Records: 1 Duplicates: 0 Warnings: 0

Show _ rowid

Mysql > select _ rowid from tweets rows in set + | _ rowid | +-+ | 1 | | 2 | +-+ 2 rows in set (0.00 sec) mysql > select _ ROWID from tweets rows in set + | _ ROWID | +-+ | 1 | 2 | +-+ 2 sec)

Show _ rowid and some columns

Mysql > select _ rowid,a from tactile rowidths-1 | 1 | 1 | 2 | 2 | +-+ 2 rows in set (0.00 sec)

Show _ rowid and all columns

Mysql > select _ rowid,a,b from tactile rowidths + | _ rowid | a | b | +-+-- +-+ | 1 | 1 | 1 | 2 | 2 | +-+-- + 2 rows in set (0.00 sec)

Cannot display _ rowid and *

Mysql > select _ rowid,* from tweets widgets and error 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near'* from tweets widgets'at line 1mysql >

_ rowid does not apply to the following scenarios:

The data type of a primary key column or a normal column is not a numeric type

The primary key is the federated primary key

The only column is not empty

This is the answer to the question about how to understand mysql 5.7 _ rowid false list. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.