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Session object 1. Introduction Session object is the object of database session, which provides the method of interaction with database session object is thread unsafe, so it cannot be used as a global variable 2. Obtaining and closing the session object How to get / create and close: //Get new session object (not commonly us ...

order This paper mainly studies MysqlPositionStore of maxwell MysqlPositionStore maxwell-1.25.1/src/main/java/com/zendesk/maxwell/schema/MysqlPositionStore.java public class MysqlPositionStore { static final Logger LOGGER = LoggerFactory.getLogger(MysqlPositionStore.class); private static final Long DEFAULT_GTID_SERVER_ID = new Long(0); priv ...

2, mysql installation and startup 1. How to install mysql 1.RPM, Yum: easy to install, fast to install, unable to customize 2. Binary: it does not need to be installed, can be used after decompression, and cannot be customized 3. Compile and install: customizable, slow to install. Before 5.5:. / configure make make install After 5.5: cmakegm ...

In the actual development, the operation of database often involves multiple tables, which involves the relationship between objects in object-oriented. For multi table operations, MyBatis provides association mapping. Through association mapping, the association relationship between objects can be well handled. Catalog What y ...

Let's learn how to use the golang Context and how to implement it in the Standard Library. The golang context package started as a Golang package used internally by Google and was officially introduced into the Standard Library in Golang version 1.7.Start learning below. Brief introduction Before learning about context packages, look at several ...

Building database and table: if DB_id('TicketManager ')is not null --Judge whether the database already exists drop database TicketManager --Remove the existing database go create database TicketManager --New database on ( name='TicketManager ',--Database name filename='E:\CS Review cases of Architecture\TicketManager\DB\TicketManager. ...

SQLite realizes user login function void login::on_LoginToMain_clicked() { //The login button needs to determine whether the user name and password correspond correctly //If there is an error, a prompt dialog box will pop up //-------------------------------------- //Use SQlite to compare user name and password QSqlDa ...

1,ANALYZE Actually execute the actual SQL, and see the time of each step of the execution plan 2,VERBOSE Additional information for explicit planning, additional information: columns output by each node in the planning tree. The trigger being fired also displays the name of the initiator. The default is FALSE. 3,COS ...

background I don't know if there is such a puzzle in your company. Many departments often ask your department to provide interfaces to query some data. The interface basically has no business logic. An SQL is enough, but it takes time and effort to develop an interface for this SQL. Many people also want to solve it. For example, they often wri ...

The difference between sql join on and where explain select count(1) from cellinfo_20171124 ci join shandong_lac_ci slc on concat(cast(ci.lac as string),",",cast(ci.ci as string)) =slc.lac_ci; | == Physical Plan == *HashAggregate(keys=[], functions=[count(1)]) +- Exchange SinglePartition +- *HashAggregate(keys=[ ...