Could not create connection to database server.

在使用jdbc语句时发生sql语句异常

警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@170312f6 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.

结果查找异常的原因，不是语句写错，依赖也导入了，但依然报错

当我换了mysql的版本号时异常解决了，原来是我的mysql的版本号过低

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