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This paper connects MyBatis basic learning knowledge point 1 and continues to discuss the following two issues         1. What is Dao configuration file mainly used for? How to configure?         2. How to test program running with test method? What does each stat ...

1, Create library and table classes create database a;//Create database //Create table create table name( Field name char(10), Field name 2 char(10) ) drop Command is also the method of use 2, Modify table data alter sentence //Delete column alter table student drop column Field name; //Add column alter table student add column Field na ...

Date: February 4 1. Higher order function What is a Function: a Function is a data type [Function] Function that can be defined by an expression Higher order function: since a function is of a type and can be used as a parameter or return value of another function, the function is called a higher-order function (simply a function calling fu ...

Reference articles Nanshen blog: https://www.wlhhlc.top/ y4 blog: https://y4tacker.blog.csdn.net/ feng blog: https://ego00.blog.csdn.net/ sql injection Let's just start sql injection now. web171 Just after entering, we can see that there are three columns: id, username and password The statement is $sql = "select username,passwor ...

MySQL database basic topic is coming! Hee-hee, this term I learned the fundamentals of MySQL database, and then I have sorted out some simple questions that are useful for MySQL database, I hope you can help! Say nothing, go dry! Table structure management 1. Objectives 1. Creation and deletion of MySQL database 2. Create, modify, delete ...

Operation of summary table Summarize according to Master Kang's video tutorial, which is convenient for individuals to review, query and use Create and manage tables #Create database CREATE DATABASE IF NOT EXISTS XXXXXX; # CREATE DATABASE XXXXXX CHARACTER SET 'UTF8'; #Use database USE XXXXXX; #modify the database ALTER DATABASE xxxxxx CHARA ...

1. Index index 1. Definition Indexing is a fast, ordered data structure that helps databases efficiently retrieve data. In addition to data, the database system maintains data structures (additional storage space) that satisfy specific lookup algorithms, which point to the data in some way so that efficient lookup algorithms can be implemente ...

Introduction: in the morning, I received a text message with the content of "Dear Hello, XXX". At that time, I smiled. It's a joke that programmers can Get. It shows that the program doesn't Get my name correctly from the database, and then formats the null value as null. To get back to business, the reason for this situation i ...

The order information table records the information of Brazilian passengers using taxi software, including order call, response, cancellation and completion time. -order_id: order ID，Call order ID -passenger_id:passenger ID，Passenger identification number -call_time:Call time, the time point when the passenger sends the request for car use f ...

Set operation of table, addition and subtraction A set represents "the sum of all kinds of things" in the field of mathematics and a set of records in the field of database Specifically, the execution results of tables, views and queries are a collection of records, in which the elements are each row in the table or query results. In ...