【解决方法】Unknown system variable ‘tx_isolation‘

查看MySQL事物的隔离级别报错：

mysql> select @@tx_isolation;
ERROR 1193 (HY000): Unknown system variable 'tx_isolation'

老版本MySQL叫tx_isolation
MySQL8叫transaction_isolation

mysql> select @@transaction_isolation;
+-------------------------+
| @@transaction_isolation |
+-------------------------+
| REPEATABLE-READ         |
+-------------------------+
1 row in set (0.00 sec)

mysql> select @@session.transaction_isolation;
+---------------------------------+
| @@session.transaction_isolation |
+---------------------------------+
| REPEATABLE-READ                 |
+---------------------------------+
1 row in set (0.00 sec)

mysql> select @@global.transaction_isolation;
+--------------------------------+
| @@global.transaction_isolation |
+--------------------------------+
| REPEATABLE-READ                |
+--------------------------------+
1 row in set (0.00 sec)