Add an auto-increment primary key column to the MySQL table

When I added a primary key to a Mysql table, I used the following SQL statement:

1. Alter Table'Table name'Add Column'Column name'Int Not NullAuto_increment comment'Primary key'Before 'a column name ';

The following two errors are returned:

1. Error Code: 1064
2. 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 'before column name' at line 1
3. (0 MS taken)

This error indicates a syntax error near before.

1. Error Code: 1075
2. Incorrect table definition; there can be only one auto column and it must be defined as a key
3. (0 MS taken)

This error indicates that only the primary key can specify auto-increment columns.

I found the reason on the internet, saying that I want to add a column before modifying the column. I think this is quite troublesome. I tried it myself and I can do it in one sentence:

1. Alter Table'Table name'Add Column'Column name'Int Not NullAuto_incrementPrimary KeyComment'Primary key' First;

The preceding statement adds an Automatically increasing primary key field to a table and places the field in the first column.

If you want to put it behind other columns, you canFirstChangeAfter 'existing column name'