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select coalesce(t.name,'总'),sum(t.v) from (select '小丽' as name,1 as v UNION ALL select '小丽' as name,2 as v ) t group by t.name with ROLLUP with ROLLUP 阅读全文
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how-to-fix-java-io-notserializableexception-org-apache-kafka-clients-consumer The Kafka Consumer record object is received from Dstream. When you try 阅读全文
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注解之前spring怎么装配bean 传统的Spring做法是使用.xml文件来对bean进行注入或者是配置aop、事务。我们先看一个不使用注解的Spring示例,在这个示例的基础上,改成注解版本的,这样也能看出使用与不使用注解之间的区别,先定义一个老师: public class Teacher{ 阅读全文