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1 what is a stored procedure (a set of sql statements compiled in advance and stored in the database) 1.1 Stored Procedure In a large database system, a set of SQL statements to complete specific functions are stored in the database and called again after the first compilation. There is no need to compile again. The user calls the stored proc ...

Current computer tool environment: IDEA, JDK1.8, Mysql5.0, Maven 3.6.1 Steps: 1. Create JAVA WEB project 2. Configure tomcat 3. Load the dependent jar package of mybatis, the dependent jar package of mysql, and the jar packages of junit and hamcrest core (as well as the jar package of log) required for configuration 4. Create a Resources f ...

SQL Server 2008 database structure System database master A database that records all system level information of the SQL Server systemmsdbTemplate database for all user databases and tempdb databasemodelUsed by SQL Server agent to schedule alerts and jobstempGlobal resources available to all users connected to the SQL Server instance, save a ...

This article is about Learning Guide for Big Data Specialists from Zero (Full Upgrade) ClickHouse: Partial supplement. 0 ClickHouse syntax optimization rules ClickHouse's SQL optimization rules are based on RBO(Rule Based Optimization). Here are some optimization rules 1 Prepare test tables 1) Upload official datasets Upload visits_v1.ta ...

Database foundation Database: a collection that stores, maintains, and manages dataDataBase Management System (DBMS) Common database management system Oracle Relational type MySQL Relational type DB2 Microsoft SQL Server Three paradigms First normal form (1NF): no duplicate columns;The second normal form (2NF): attributes are complete ...

1. Introduction to database Baidu's definition of database is: "database is" a warehouse for organizing, storing and managing data according to data structure ". It is a collection of large amounts of data stored in computers for a long time, organized, shareable and uniformly managed." In short, a database is a collec ...

SQL basics tutorial Statement: the content of this blog is sorted out from Datawhale's punch in learning, and sorted into notes according to the punch in content. For reprint, please contact Datawhale and my authorization, and the reprint source must be indicated. Chapter 3 more complex queries The first two punch in notes introduced th ...

preface: Will MySQL restrict login when there are too many failures to connect to the database? How should the database server deal with violent cracking? This article introduces the connection control plug-in in MySQL. Let's learn the role of this plug-in. 1. Introduction to connection_control plug-in MySQL server contains a plug-in library ...

First, let's simulate a business scenario. If we have such a master data table: In order to find the information of this master data, we let each field participate in the query:   The category is master data: Now you need to develop an API locally to call external systems. Transmission mode: POSTThe data format of request and res ...

1. Second kill code (most low implementation): //Open transaction @Transactional(rollbackFor = Exception.class) public BaseResponse<?> startSeckillWithLock(Long id, Long userId) { try { return seckill(id, userId); } catch (Exception e) { throw e; } finally { } } p ...