服务器发生错误时所提供的唯一错误码，打印在 Proxy 后端或 JDBC 启动日志中。
| 错误码 | 错误信息 |
|---|---|
| SPI-00001 | No implementation class load from SPI `%s` with type `%s`. |
| DATA-SOURCE-00001 | Data source unavailable. |
| PROPS-00001 | Value `%s` of `%s` cannot convert to type `%s`. |
| PROXY-00001 | Load database server info failed. |
| SPRING-00001 | Can not find JNDI data source. |
| SPRING-SHARDING-00001 | Can not support type `%s`. |