Spring Boot 数据库连接错误：Unknown database 'ry' 解决方法

Spring Boot 数据库连接错误：Unknown database 'ry'

该错误是由于无法连接到数据库导致的。具体原因可能是数据库配置错误、数据库未启动或数据库不存在。

解决方法如下：

1. 检查数据库配置是否正确，确保数据库名称、用户名和密码正确。

2. 检查数据库是否已启动。可以尝试使用数据库管理工具连接数据库，确认数据库是否正常工作。

3. 如果数据库不存在，请创建一个空数据库，并确保数据库名称与配置文件中的数据库名称一致。

4. 如果使用的是MySQL数据库，可以尝试执行以下命令来创建数据库：

   create database 'ry';
   

   然后重新启动应用程序。

5. 如果以上步骤都没有解决问题，可以尝试重启数据库服务。

如果问题仍然存在，请提供更多详细的错误日志和配置信息，以便进一步分析和解决该问题。

错误信息

Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLSyntaxErrorException: Unknown database 'ry'
### The error may exist in URL [jar:file:/usr/local/nginx/html/ruoyi-admin.jar!/BOOT-INF/lib/ruoyi-system-4.7.4.jar!/mapper/system/SysConfigMapper.xml]
### The error may involve com.ruoyi.system.mapper.SysConfigMapper.selectConfigList
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLSyntaxErrorException: Unknown database 'ry'
        at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:153)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:145)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:427)
        ... 124 common frames omitted
Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLSyntaxErrorException: Unknown database 'ry'
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:83)
        at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80)
        at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)
        at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337)
        at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86)
        at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
        at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325)
        at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
        at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
        at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:89)
        at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:151)
        ... 131 common frames omitted
Caused by: java.sql.SQLSyntaxErrorException: Unknown database 'ry'
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828)
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448)
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241)
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
        at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:156)
        at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:251)
        at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:150)
        at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1659)
        at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1723)
        at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:927)
        at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1401)
        at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1397)
        at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:100)
        at org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource.getConnection(AbstractRoutingDataSource.java:194)
        at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:159)
        at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:117)
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
        ... 141 common frames omitted