一次数据库查询超时优化问题的实战记录（数据库查询超时时间）居然可以这样

文章摘要

这篇文章报告了一个MySQL JDBC连接异常，错误类型为`com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command`。错误信息显示，问题可能与`mapper/XXXXXXXXX-Mapper.xml`或`mapper/XXXXXXXXXOMapper.xml`的类路径资源相关，也可能涉及到`defaultParameterMap`。错误发生在设置数据库参数的过程中，涉及的SQL查询语句较为复杂。为解决此问题，建议检查相关配置文件和SQL语句的正确性，并确保使用了有效的数据库连接方案。

### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command
### The error may exist in class path resource [mapper/XXXXXXXXX-Mapper.xml]
### The error may involve defaultParameterMap
### The error occurred while setting parameters
### SQL: select t3.cino, t2.sn as orderSn, t2.provider_id as providerId, t4.logistics_no as logisticsSn, t2.`name`,
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command
; Unsupported command; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command
org.springframework.dao.DataAccessResourceFailureException:
### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command
### The error may exist in class path resource [mapper/XXXXXXXXXOMapper.xml]
### The error may involve defaultParameterMap
### The error occurred while setting parameters
### SQL: select t3.cino, t2.sn as orderSn, t2.provider_id as providerId, t4.logistics_no as logisticsSn,
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Unsupported command