【MySQL】更改表的主键报错及解决办法

报错：

[HY000][3750] Unable to create or change a table without a primary key, when the system variable ‘sql_require_primary_key’ is set. Add a primary key to the table or unset this variable to avoid this message. Note that tables without a primary key can cause performance problems in row-based replication, so please consult your DBA before changing this setting.

出现场景：想要使用以下语句更改数据库的主键

alter table A
    drop primary key;

alter table A
    add primary key (id);

解决办法：把两条语句写成一条即可

alter table A
    drop primary key,
    add primary key (id);