8KW Dry Goods Tutorial | Reflective lecture on java

Reflection mechanism in java Catalog1. The concept of reflection mechanism2. Base Class of Reflection3. Usage of reflection4. Examples of applications of reflection Author's introduction: A stack of learning notes, a person working hard The concept of reflection mechanism: In the run state, all the properties and methods of this class can be ob ...

Posted by brianlange on Sun, 29 Mar 2020 20:44:53 -0700

Java database development (1): JDBC connection database

1, MySQL database 1. Create database CREATE DATABASE jdbc CHARACTER SET 'utf8'; 2. build tables CREATE TABLE user ( id int(10) NOT NULL AUTO_INCREMENT, userName varchar(20) NOT NULL, PRIMARY KEY (id) ); 3. Add data 2, Connect MySQL database through JDBC 1.JDBC URL 2.Statement boolean execute(String SQL): if the ResultSet object can be ...

Posted by katlis on Sun, 29 Mar 2020 11:35:55 -0700

oracle stored procedure II

Parameterless stored procedure: create or replace procedure sayhello as --Explanation part begin dbms_output.put_line('hello world'); end; 1 2 3 4 5 6 Two call methods of command window 1. SQL> set serveroutput on; --The first time I have to drive SQL> exec sayhello hello world PL/SQL procedure successfully comple ...

Posted by joenjeru on Sun, 29 Mar 2020 09:34:56 -0700

8, PlSql programming of Oracle

1. PlSql programming procedure language In the sql statement of database, the common definition of variable condition judgment cycle structure is added to the statement of process 1) . basic grammatical structure declare – declaration part – similar to defining variables begin &nda ...

Posted by jayd1985 on Sun, 29 Mar 2020 09:01:48 -0700

Storage of spatial data and generation of heat map by GeoServer

The requirements are as follows. There are already generated good spatial data, including date, hour, longitude, latitude, number of people. Use GeoServer to generate heat map. This article uses the PostgreSQL10 database and has added PostGIS support. Create table create table table_test( day varchar(8), hour int, lon nu ...

Posted by bob1660 on Sun, 29 Mar 2020 08:18:17 -0700

Hive is finally waiting, Flink

When did Apache Spark start to support the integrated Hive feature? I believe that as long as readers have used Spark, they will say that this is a long time ago. When does Apache Flink support integration with Hive? Readers may be confused. Haven't they supported it yet, haven't they used it? Or the latest version only supports it, but the fu ...

Posted by elfeste on Fri, 27 Mar 2020 03:09:45 -0700

[HQL] HQL realizes the change of daily order quantity, order quantity without address and order quantity without address N days later

The original table (order? TBL) is partitioned by dt, and the full order is saved by partition every day (zone 20200321) order_id address trade_time dt 1 Tianjin 20200320 20200321 2 Beijing 20200320 20200321 3 Beijing 20200319 20200321 4 Tianjin 20200319 20200321 5 Beijing 20200321 20200321 6 20200321 20200321 (zone 20200320) ...

Posted by wendu on Thu, 26 Mar 2020 07:10:56 -0700

Performance comparison between golang sqlx and db.v3

Recently, when communicating with a big guy, I mentioned the problem of SQL query. His idea is to query data with the most primitive database driver without ORM. The benefits of doing so are twofold Express SQL semantics clearly for later optimization. Especially in report, data analysis and other complex SQL. Reduce useless encapsulation and ...

Posted by Sravan on Tue, 24 Mar 2020 07:29:38 -0700

Do you really change your status?

In enterprise applications, there are too many scenarios involving modifying state. For example, after an enterprise enters the network, it needs to check its qualification. After the individual receives the task, the enterprise administrator shall review the receiver. In the application management system, usually as shown in the figure below, ...

Posted by Pastulio on Mon, 23 Mar 2020 06:45:23 -0700

Use of ControllerAdvice annotations

In order to facilitate the unified management of exceptions, spring mvc provides controlleradvise annotation to deal with exceptions in a unified way. After getting the exception information, you can sit and handle it. For example, it provides a unified web interface to view the exception information, or it sends SMS or email t ...

Posted by Zaid on Fri, 20 Mar 2020 12:20:20 -0700