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java basics

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java basics

hadoop offline day08--data warehouse, Apache Hive

hadoop offline day08--data warehouse, Apache HiveToday's content outline#1、数据仓库基础知识 数仓是什么 数据分析的平台 面向分析 数仓由何而来 数仓核心特性 数仓和数据库区别 解决一个核心的误区:数仓绝不是大型数据库。~~~ 凉凉 OLTP T 事务 OLAP A 分析 数仓的分层架构 #2、当下大数据领域最著名的数仓软件 Apache Hive Hive是什么 数仓 基于Hadoop的数仓 如何理解和Hadoop关系 核心功能:   1、将结构化文件映射成为一张表(Table)   2、基于表提供了SQL分析能力 (Hive SQL HQL,类SQL)   本质:用户HQL--->Hive转换MR--->数据分析

java basics

Java study notes-JDBC

Article DirectoryJDBCWhat is JDBCJDBC core APIDriverManager class-drive management objectConnection interface: database connection objectStatement: the object that executes sqlExecute DML statementPerform DQL operationsResultSet interfaceSmall exercise-database tools JdbcUtilsPreparedStatement: the object that executes sqlPerform DML operationsJDBC transaction processingJDBC Batch batch operationDatabase connection poolJDBCWhat is JDBCThe JDBC specification defines the interface, and the specific

spring

Transaction nesting in Spring: Transaction rolled back because it has been marked as rollback-only exception handling

Transaction nesting in Springboot: Transaction rolled back because it has been marked as rollback-only exception handling1. Basic introduction to the experiment2. Experimental process2.1 Method A adds transactions, method B does not add transactions, and method A captures the exception of method B, then the result at this time:-------Neither