MyBatis Plus-4-Conditional Constructor

Conditional constructor 1.1 EntityWrapper Mybatis-Plus constructs query conditions through Entity Wrapper (EW, a query condition constructor encapsulated by MP) or Condition (similar to EW), which is simple and convenient! Entity wrapper, mainly used to deal with sql splicing, sorting, entity parameter query, etc. Entity Wrapper inherits Wrapp ...

Posted on Sat, 05 Oct 2019 21:59:19 -0700 by Hokus

Dynamic SQL of MyBatis-Mapper File

if tags <if test="OGNL expression"> When the test is true </if> eg: <if test="id != null"> id=#{id} </if> <if test="id != null and username.trim() != ''"> id=#{id} </if> <if test="id == 0 or username.trim() != ''"> id=#{id} </if ...

Posted on Sat, 05 Oct 2019 04:23:45 -0700 by rogeriobrito

Addition, deletion and modification of Oracle database

Database modification & data backup - database modification & data backup Note: After the execution of the deleted modified data SQL statement, it will not enter the data writing immediately. - You also need to submit data manually and roll back if there is a problem with the data. Primary key ...

Posted on Sat, 05 Oct 2019 02:56:03 -0700 by netpants

Realization of ATM ATM System by Python

Python implements ATM Realization of ATM ATM System by Python [csdn blog portal] (https://blog.csdn.net/zhanghao 3389) [github blog portal] (https://mrzhang3389.github.io/) Boring wrote a ATM ATM system, there is a small bug does not affect the use of Knowledge required for this chapter: 1. Simple SQL statements (build database, build tables, a ...

Posted on Sat, 05 Oct 2019 00:28:56 -0700 by bwochinski

Mysql Stored Procedures

stored procedure know In some programming languages, such as pascal, there is a concept called "process" and "function", such as sub. Java, Python, PHP in VB, no process, only function. Procedure: Several statements are encapsulated and executed when invoked. Function: A process with a return value (ps: Python function is bo ...

Posted on Fri, 04 Oct 2019 14:11:12 -0700 by gladius

Redis from Cognitive Installation to Implementing CURD

Redis knows nothing but knows a little. Redis is an open source, support network, memory based and optional persistence key value pair storage database written by ANSI C. Simply put, Redis is a high-performance NOS QL database What is NoSQL? The MySQL database we learned before is a typical SQL database, that is, the traditional relational dat ...

Posted on Fri, 04 Oct 2019 13:17:19 -0700 by jroodman

Detailed description of JDBC query method execution process

Detailed description of JDBC query method execution process import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; interface IRowMapper{ void rowMapper(ResultSet resultSet); } public class Select { //Detailed description of JDBC query method execution process //Goal ...

Posted on Fri, 04 Oct 2019 02:56:50 -0700 by magicdanw

Mybatis XML mapping file

mybatis is built to focus on SQL, the top-level elements commonly used in SQL mapping files, such as resultMap, the most complex and powerful element, describes how to load objects from the database result set.   Insert, mapping insert statement update, mapping update statement Delete, mapping delete statement select, mapping query s ...

Posted on Thu, 03 Oct 2019 22:07:26 -0700 by simonsays

oracle Basic Knowledge Accumulation - Create Packages and Packages bodies

Scene: Basic Knowledge Query Motivation: Pure basic knowledge is accumulated to facilitate follow-up inquiries. In many occasions, people in charge are talking about going to IOE. Therefore, inevitably, the use of occasions will be more or less reduced, so according to the customary thinking record. ...

Posted on Thu, 03 Oct 2019 16:29:49 -0700 by bough

Lucene 5.2.1 + jcseg 1.9.6 Chinese indexing index (Lucene learning sequence 2)

Links to the original text: https://my.oschina.net/qiuzhping/blog/611692 Lucene 5.2.1 + jcseg 1.9.6 Chinese indexing index (Lucene learning sequence 2) jcseg is used Java Developing a ...

Posted on Thu, 03 Oct 2019 11:45:29 -0700 by ktstowell