Database Experiment 2

Experiment 2: create and manage database Experimental content 1. Create database Assume that the SQL Server service has been started and log in to the computer as Administrator (the file name is customized); Please use the Management interface mode and T-SQL statement respectively to realize the following operations: It is required to create ...

Posted on Sat, 20 Nov 2021 07:02:17 -0500 by The Swedish Tower

❤️ Liver explosion for 3 days! 20000 word graphic SQL zero basic entry, not afraid you can't learn, just afraid you don't collect! ❤️

📚 preface SQL language has a history of more than 40 years. Since it was applied, it has been almost everywhere. Every payment record we consume, every user information we collect and every message we send will be stored in the database or its related products, and the language to manipulate the database is SQL! SQL is almost a necessar ...

Posted on Sat, 20 Nov 2021 06:42:25 -0500 by phpBever

MySQL master-slave replication

1, Introduction to master-slave replication 1.1 what is master-slave replication Copy the binlog log of the master server to the slave server for execution to achieve the consistent state of the master-slave data, which is called master-slave replication. In a word, what the master database does is what the slave database does. 1.2 why s ...

Posted on Fri, 19 Nov 2021 18:28:24 -0500 by ravira

hiveSQL execution plan (explain the most detailed in the whole network!!)

0 - Preface Hive SQL's execution plan describes the overall outline of the actual execution of SQL. Through the execution plan, you can understand the execution logic of the SQL program when it is converted into the corresponding computing engine. If you master the execution logic, you can better grasp the bottleneck of the program, so ...

Posted on Fri, 19 Nov 2021 18:11:54 -0500 by XxDeadmanxX

Grouping and filtering of DQL statements

Note: the following will use the emp table in the mysql database in the mysql database management system as an example This content continues from the previous study notes: DQL statement 2 in SQL (learning note 3) 1, Grouping function Grouping function is also called multi line processing function, and there are only 5 multi line proce ...

Posted on Fri, 19 Nov 2021 13:32:06 -0500 by nainil

[crazy God Theory] mysql self-study summary chapter 10

preface This is the self-study notes of crazy God's mysql, which is only for reference, learning and continuous updating The following is a video learning link: https://www.bilibili.com/video/BV1NJ411J79W 10. JDBC (key) 10.1. Database driver Driver: sound card, graphics card, database Our program will deal with the database throug ...

Posted on Fri, 19 Nov 2021 07:26:42 -0500 by lucifer27

Summarize knowledge points in the data

mysql database notes DQL: query statement 1. Sort query 2. Aggregate function 3. Group query 4. Paging query constraint Relationship between multiple tables normal form Backup and restore of database DQL: query statement Sort query Syntax: order by clause order by sort field 1, sort by 1, sort field 2, sort by 2 Sort by: ...

Posted on Fri, 19 Nov 2021 02:39:08 -0500 by thecard

Solutions to errors in ORACLE SELECT INTO syntax ORA-01422 and ORA-01403

background In Oracle functions or stored procedures, the following syntax is usually used to assign values to variables: -- Single variable assignment SELECT [Field 1] INTO [Variable 1] FROM [data sheet] WHERE [query criteria]; -- Multivariable assignment SELECT [Field 1], [Field 2] INTO [Variable 1], [Variable 2] FROM [data sheet] WHERE [qu ...

Posted on Fri, 19 Nov 2021 01:45:29 -0500 by lead2gold

Detailed clearance course of xss shooting range of pikachu

Hair Tip: after the article is written, the directory can be generated automatically. Please refer to the help document on the right for how to generate it Less-1 reflective xss(get) Let's input some special characters first to see if there are any special characters filtered out. Click Submit, as shown in the figure ' '' <>6666 ...

Posted on Thu, 18 Nov 2021 08:53:05 -0500 by trube

MySQL - triggers and events

trigger We may have the following requirements when using MySQL: Before inserting or updating data into t1 table, the data is automatically verified. The value of m1 column must be between 1 and 10. The verification rules are as follows: If the value of the m1 column of the inserted record is less than 1, press 1 to insert.If the value of ...

Posted on Wed, 17 Nov 2021 21:05:06 -0500 by sneamia