1a23-pangqiu

mycat执行语句select 1 from dual报错dual表不存在, dual本来就是mysql的虚拟表本来就不存在, mycat不支持mysql的语法

Mycat2-1.22 Mysql隔离级别是RC, Mycat是RR, 两者不统一, 更改Mycat事务隔离级别不生效, 如下: 配置用户 ``` { "dialect":"mysql", "ip":null, "password":"123456", "transactionType":"proxy", "username":"root", "isolation":2 } isolation 设置初始化的事务隔离级别 READ_UNCOMMITTED:1 READ_COMMITTED:2 REPEATED_READ:3,默认 SERIALIZABLE:4 ``` 重启Mycat之后查询事务级别还是RR, 不是RC 

SQLParsingException: no viable alternative at input

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## Bug Report ### Which version of ShardingSphere did you use? 5.3.2 ### Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy? ShardingSphere-JDBC ### Expected behavior sql correct ### Actual behavior...