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  Handwritten database connection and test   Recently, to connect to GP database (Greenplum SQL), you need to establish different number of connections In fact, when you want to write database connection, you can write interface directly through springdata jpa, which is a kind of thinking So in the use, I wrote a demo to t ...

1. In the actual application scenario, we will use: if the data is in the table, update the data; if the data does not exist, insert the data. In oracle, you can use the merge into implementation, and in mysql, you can use the ON DUPLICATE KEY UPDATE. Here, only the merge into implementation method in oracle is introduced. The sql syntax is a ...

First, we need to create an empty examstudent table in the database: Second, create a student class corresponding to the contents in the table: package com.atguigu.jdbc; public class Student { // Serial number private int flowId; // Examination type private int type; // ID number private String idCard; // Ticket num ...

When you want to insert a large amount of data into the database, using insert is not only inefficient, but also causes a series of database performance problems When inserting data using insert statements. I used two methods: Each time you insert data, only one database will be inserted, which will lead to the continuous opening and closing ...

target The config module refers to the implementation mode, interface and implementation separation in database/sql. In this tutorial, the implementation of ini format configuration is selected and the integration mode of beego and config module is analyzed to achieve the following three goals. Understand the source code implementation of conf ...

"High efficiency" means the speed of table building is fast? no, it's 9012 years. What do you want? Efficient table creation refers to how to quickly query this table. Under the same resource conditions, the query performance is better than that of ordinary tables!When we build a table, we usually attach attributes to the table, such ...

scene Introduction to JPA and HelloWorld (with code download): https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/103473937 Implement one-way many-to-one associations in JPA: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/103511623 One-way one-to-many associations are implemented in JPA: https://blog.csdn.net/BADAO_LIUMANG_QIZ ...

Today, I saw a blog post on the Internet. The title is: insert 10 million pieces of data into mysql database in 4 minutes. I think it's very interesting, so I record it for myself to learn.MySQL version: mysql-5.7.22-winx64 1. Set the capacity of MySQL database tables The default capacity of the database table is 4M. If the stored data exceeds ...

The importance of data backup 1. In the production environment, the safety of data is very important, and any loss of data may have serious consequences 2. Causes of data loss Program error Human error Computer failure Disk failure Disaster and theft Classification of database backup From a physical and logical point of view, backup can be d ...

Requirement: read out the data in hive and write it into es. Environment: spark 2.0.2 1. enableHiveSupport() is set in sparksession SparkConf conf = new SparkConf().setAppName("appName").setMaster("local[*]"); SparkSession spark = SparkSession .builder() .appName("Java Spark SQL basic exam ...