Tag：Sentence
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Time：2021-7-31
When using gin Gorm, the default SQL statement is printed on the terminal. If you want to record it to a file, you can use logrus to record it to a file First, do some configuration of logrus package tools import ( “fmt” “github.com/gin-gonic/gin” “github.com/sirupsen/logrus” “os” “path” “time” ) func Logger() *logrus.Logger { now := […]
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Time：2021-7-30
Author:Hans J ü rgensch ö nig, he has used PostgreSQL since the 1990s. He is the CEO and technical leader of cybertec. Cybertec is one of the market leaders in this field and has provided services to countless customers around the world since 2000. The second edition of PostgreSQL 9 and PostgreSQL 6 has been […]
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Time：2021-7-30
Dynamic SQL if Include according to conditionswherePart of clause <select id=”findActiveBlogLike” resultType=”Blog”> SELECT * FROM BLOG WHERE state = ‘ACTIVE’ <where> <if test=”title != null”> AND title like #{title} </if> <if test=”author != null and author.name != null”> AND author_name like #{author.name} </if> </where> </select> Then< where >Don’t add the first conditionAND choose-when-otherwise Don’t use […]
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Time：2021-7-29
1、 BackgroundWhen the application system connects to the Oracle database, the author needs to use English uniformly. The configuration cannot be modified on the database server side, because some methods need to be found on the application system side.2、 SolutionAfter consulting the data source and mybatis related source code, there are two ways to support […]
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Time：2021-7-28
What is explain Using the optimizer can simulate the optimizer to execute SQL query statements, so as to know how MySQL handles your SQL statements, and analyze the performance bottlenecks of your query statements and table structures. What can explain do Sequential reading of tables Which indexes can be used Operation type of data read […]
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Time：2021-7-27
To bind to an event, use the event binding syntax of angular. This syntax consists of the target event name in parentheses to the left of the equal sign and the template statement in quotation marks to the right. In the following example, the target event name is click and the template statement is onsave […]
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Time：2021-7-27
preface We areLast articleThe use skills of various operators are described in, followed by the contents of the previous article. This article mainly focuses on process control. The main contents of the article are arranged as follows: Input and output Conditional judgment Control cycle Input and output input To input from the console and read […]
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Time：2021-7-26
There are two kinds of locksShared lock: Select… Lock in share modeExclusive lock: Select… For update 1. Submit the exclusive lock manually Turn off MySQL auto commitSet autocommit = 0; Window 1 execute command mysql> select * from stu where id=1 for update; +—-+——+—–+———+ | id | name | num | version | +—-+——+—–+———+ |1 […]
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Time：2021-7-25
Subqueries and special queries (Union and limit) The syntax of sub query and special query in MySQL is summarized Subquery Sub queries are divided intoSubquery in where statement、Subquery in from statement、Subquery in select statement Because the subquery in the select statement is rarely used, the following tests only correspond to the subquery in the where […]
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Time：2021-7-23
Translation link:https://www.infoworld.com/art… The concept of object relational mapping (ORM) has existed for a long time. The function of ORM is to solve the problem of mismatch between object model in programming field and data model in relational database. Dapper is an open source and lightweight ORM framework developed by stack overflow team, The biggest advantage […]
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Time：2021-7-23
1、 Install related packages npm install access-db npm install dotenv Then it is introduced at the front of the project entry file (such as app. JS)require(‘dotenv’).config() newly build.envFile, and add MySQL configuration. MYSQL_ Host = localhost // required MYSQL_USER=root MYSQL_PASSWORD=123456 MYSQL_PORT=3306 MYSQL_ Database = // required database name 2、 Transaction and lock transaction () Asynchronous […]
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Time：2021-7-23
catalogue preface 1. Create 1.1 create database 1.2 form creation 1.3 index creation 1.4 create primary keys for existing columns 1.5 create incremental constraints for existing columns 2. Insert 3. Modification 3.1 modifying data records 3.2 modify the database character set to utf8 3.3 modify the table character set to utf8 3.4 modify the table […]
