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Database transaction Introduction to database transactions 1. Transaction: a group of logical operation units that transform data from one state to another. 2. Transaction processing (transaction operation): ensure that all transactions are executed as a work unit. Even if there is a fault, it cannot be modified Change this way of execution ...

1, Design table Premise: the design table should first follow the three paradigms as needed Review 3NF: 1NF – > column is the smallest atom that cannot be subdivided (avoid duplication);2NF – > primary key dependency (unique);3NF – > eliminate the transfer dependency (establish the primary foreign key Associati ...

This tutorial will show you how to quickly build streaming ETL for MySQL and Postgres based on Flink CDC.Flink-CDC project address:https://github.com/ververica/flink-cdc-connectorsThis tutorial's demo is based on a Docker environment and will be done in the Flink SQL CLI, involving only SQL, without a single line of Java/Scala code, or with an ...

catalogue Log type and function: 1.redo redo log 2.undo rollback log 3.errorlog error log 4.slow query log 5.bin log binary log 6.relay log 7.general log Log query           Importance of data backup Classification of database backup Common backup methods Actual operation Physical cold backup and recover ...

Transferred from: Micro reading (www.weidianyuedu.com) Micro reading - complete collection of model articles - a website for free learning knowledge First, let's take a look at the code for obtaining four thread pools: ExecutorService fixedThreadPool = Executors.newFixedThreadPool(10); ExecutorService cachedThreadPool = Executors.ne ...

1. Common shell namecommandCreate tablecreate 'table name', 'column cluster name 1', 'column cluster name 2'get dataget 'table name', 'row key', 'column cluster name: column name'Add dataput 'table name', 'row key', 'column cluster name: column name', 'value'View all tableslistView table structuredesc 'table name'Delete columndelete 'table ...

1. Basic knowledge 1.1 A procedure for data storage Storing data is the first step in processing data. Data can only be stored correctly for efficient processing and analysis. Otherwise, it can only be a mess, unable to start. So how can we store all kinds of business-related and complex data in an orderly and efficient way? In MySQL, a ...

Experimental purpose Master the application of simple SQL query statements, including the application of conditions, like, top, order by, compute, etcMaster the application of connection query Experimental content 1. Basic query (1) Query all the information of all students in the Student table use student_info; select * from Student; ...

1. Insert Data 1.1 Mode 1: Add by VALUES Case 1: Insert data in default order for all fields of a table INSERT INTO Table Name VALUES (value1,value2,....); Each field in the table needs to be assigned a value in the value list, and the order of values must be the same as the order in which the fields in the data table are defined. ...

This is a note from October 7, 2018. At that time, a batch of amoA genes of soil ammonia oxidizing bacteria (AOA/AOB) were cloned and sequenced, and the sequencing results need to be identified in batch. In order to save time, I taught myself about the local comparison of blast. At that time, I also used the blast-2.7.1 + version. Now download ...