Execution order of Mysql statement

1. Such a question, as a developer, what should he master about the database? In the development process, the database is involved, basically only sql statements are used. How to write sql and optimize it is very important. Those thick books of mysql are aimed at DBA s, and we only need to learn the ...

Posted on Thu, 12 Mar 2020 06:11:58 -0400 by hoogeebear

Using PDO to connect database in php

Use PDO (PDO is PHP Data Object) to connect to the database. PDO provides a data access abstraction layer, which means that no matter which database is used, the same functions (Methods) can be used to query and obtain data. Single template: test.php file <?php // PDO connection database, single temp ...

Posted on Thu, 12 Mar 2020 05:00:43 -0400 by deepakagrawal1982

Database Learning 5: Introduction to Database Learning 41-50 Questions (based on MySQL)

SQL interview must have 50 questions 123 41. Query the student number, course number, and student achievement (key) of the same students in different courses. Classify by number and achievement first: SELECT s_id,s_score FROM Score GROUP BY s_id,s_score The results are as follows. The table shows ...

Posted on Sun, 08 Mar 2020 22:20:57 -0400 by Zoud

Beginner's springboot path, mybatis-plus use

0-Preface Mybatis plus is an enhancement to mybatis. After integrating mybatis plus, simple CRUD and paging are not needed to write, which is very convenient and recommended by five stars. 1-Integration 1-1, Add Dependency <!-- 9,Integrate mybatis-plus --> <dependency> <groupId>com.baomidou</gr ...

Posted on Sun, 08 Mar 2020 21:02:56 -0400 by adx

Validation of one or more entities failed while saving changes to the SQL Server database using the Entity Framework

I want to save my edits to the database. I prefer using entity framework code in ASP.NET MVC 3 / C, but I get an error. In my Event class, I have DateTime and TimeSpan data types, but in my database, I have date and time, respectively. Could that be the reason? How to convert to the appropriate data type in code before saving changes to the da ...

Posted on Sun, 08 Mar 2020 07:35:22 -0400 by Hillary

Mybatis from entry to mastery -- parameter transfer

1, Preparations 1.maven dependency <dependencies> <!-- mysql drive --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.18</version> ...

Posted on Sun, 08 Mar 2020 01:38:11 -0500 by Donovan

< PHP > small project of borrowing website

The content of the website is the pictures downloaded on dangdang.com as the filling of the page.Source code acquisition: https://github.com/akh5/PHP/tree/master/library1.1 Function and implementation code brief introduction Technology and operation environment Code volume list Function introduction ...

Posted on Sat, 07 Mar 2020 20:53:32 -0500 by msaspence

Expression of common filter conditions in SQLAlchemy ORM query

When using SQLAlchemy ORM to query data, if the required records are filtered according to the selected conditions, you can refer to the relevant methods described in this article. There's no skill, just familiarity. Use the data source I often use Sample Data . It is recommended to use jupyter noteboo ...

Posted on Sat, 07 Mar 2020 08:28:57 -0500 by ams007

On initialization of Mybatis

Introduction This article mainly talks about the source code analysis of two ways of Mybtais: the traditional way and Mapper agent way. It's the first time to explore the source code of Mybatis. I hope you don't spray and correct the mistakes. Thank you! Personal blog: www.fqcoder.cn 1, Mybatis Arch ...

Posted on Sat, 07 Mar 2020 01:53:52 -0500 by zachatk1

9, mysql optimization lock

MyISAM storage engine table lock Table read lock Read lock, everyone can read, can't write   Table write lock You can't write, you can't read   Table lock analysis View the current table lock status mysql> show open tables; +--------------------+------------ ...

Posted on Fri, 06 Mar 2020 23:02:38 -0500 by toro04