04GORM source code interpretation

brief introduction query Query process Build query SQL statement Conditional statement Summary search structure Definition of search search method Summary summary brief introduction GORM source code interpretation, based on v1.9.11 edition. query In the previous section, we explored how models are defined and how data tables are creat ...

Added by champoi on Sun, 21 Jun 2020 12:01:47 +0300

The first experience of flink streaming sql

Article catalog background Example explanation Construct the StreamTableEnvironment object Register table Using Tuple Using Row Pojo class using java Use external storage background sql,Structured Query Language: as a general and popular query language, Structured Query Language is becomin ...

Added by TodManPlaa on Sun, 21 Jun 2020 07:16:31 +0300

DQL data query language 2

DQL data query language multi-table query Cartesian set Equivalence / connection query join query join link Common functions Subquery Paging query multi-table query Cartesian set Generation conditions: Omit connection conditions Invalid connection condition All rows in all tables are connec ...

Added by nocniagenti on Thu, 18 Jun 2020 08:26:10 +0300

New feature of JDK8: date time related API

New feature of JDK8: date time related API Problems with old version date time API: 1. Poor design: in java.tilogjava Sq| has date classes in its packages, java.util.Date Contains both date and time, and java.sql.Date Only. Contains the date. In addition, the classes used for formatting and pars ...

Added by Iceman18 on Wed, 17 Jun 2020 07:06:02 +0300

Notes on Mybatis source code: from the perspective of cache system, the distribution mode of responsibility chain and enterprise level practice of circular dependence

1, Cache overview The design of Mybatis cache system follows the principle of single responsibility, opening and closing, and high decoupling. It is exquisite and fully layered, and its unique features can be applied to many similar businesses. Here is a brief analysis of the main caching system. With the help of the learning of Mybatis cache ...

Added by php_b34st on Tue, 16 Jun 2020 11:41:24 +0300

Stored procedure cursor

example: At present, there are three tables A, B and C. among them, A and B are one to many relationships, and B and C are one to many relationships. Now it is necessary to save the primary key of table A in B into C; The general idea is to query out B and update table C with an update statement, bu ...

Added by bobicles2 on Tue, 16 Jun 2020 10:41:40 +0300

django Series 5 - QuerySet API operation

QuerySet API usage QuerySet can construct, filter, slice, and approximate results without actually accessing the database. Unless you do something to evaluate the query set, no query activity actually occurs to the database. (1) Basic properties iteration The QuerySet is iterative, and its databa ...

Added by Phire on Tue, 16 Jun 2020 06:59:36 +0300

jdbc advanced custom connection pool and custom jdbc framework

JDBC advanced Use of JDBC connection pool The concept of database connection pool Database connection is a key and limited resource. When java program and database get the connection, it consumes resources especially. Therefore, a database connection pool is created to manage the connection betwe ...

Added by shane0714 on Mon, 15 Jun 2020 11:47:18 +0300

SQL Server advanced query and T-SQL programming and transaction DQL+DML+DDL+DCL to realize warehouse inventory management system (example code display)

SQL Server advanced query and T-SQL programming to realize warehouse inventory management system SQL Server advanced query and T-SQL programming SQL Server advanced query and T-SQL programming to realize warehouse inventory management system 1. Language and environment 2. Functional requirements 3 ...

Added by bleh on Sat, 13 Jun 2020 09:21:58 +0300

Kettle and Hadoop perform Sqoop jobs

catalog 1, Sqoop export 2, Sqoop import 1, Sqoop export 1. Create a job to export the HDFS file to the MySQL database. (1) Open PDI and create a new job, as shown in Figure 1. Figure 1   (2) Edit the 'Sqoop export' job item, as shown in Figure 2. Figure 2 Description: CDH631 is a buil ...

Added by cloudhybrid on Mon, 08 Jun 2020 06:13:45 +0300