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1, Question oracle's btree index does not store NULL value, so index range scanning will not be used with is null or is not null, but is this also true in mysql? 2, Experiment Let's take a look at NULL in oracle (11g) Prepare test data SQL> create table t1 as select * from dba_objects; SQL> update t1 set object_id = null where object_id & ...

I often listen to songs in NetEasy Cloud, and feel that those people have a good literary style and have commented on talents since ancient times. At the same time, I want to know what songs really make these people use their talents. Let's crawl through some of the hot song reviews. Some of the modules we'll use from Crypto.Cipher import AES ...

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Task05: window functions, etc. - Tianchi Longzhu program SQL training camp Original tutorial link Recommended reference books: SQL basics tutorial Window function Window functions are also called OLAP functions. OLAP is short for online analytical processing, which means real-time analysis and processing of database data. Conventional ...

preface Yesterday all sorts of strange things were as like as two peas in the nacos tutorial. They found that the nacos tutorial was basically a bit like the same. They were copied and copied, so that you could configure a lot of things. The introduction of dependencies was also a great surprise. Even the official tutorials of the librar ...

Node.js MySQL driver Node. The native MySQL driver library of JS is called mysql MySQL L2 project is an upgraded version of the native MySQL driver project. It is compatible with MySQL and supports its main features. It provides new features: Faster and better performancePreprocessing statementExtended support for encoding and collati ...

Is it easy to query a large amount of data? Try MySQL streaming query 1, Foreword When the program accesses the MySQL database, when the amount of data queried is particularly large, the database driver loads all the loaded data into the memory, It may lead to memory overflow (OOM). In fact, a streaming query is provided in MySQL database, wh ...

Author: Yicun HUI source: https://www.cnblogs.com/zsql/ For DBAs, data backup and recovery is a very basic operation. Under unexpected circumstances (server downtime, disk damage, RAID card damage, etc.), every DBA should be concerned about database backup at all times to ensure that data is not lost or to the minimum extent. The backup tools, ...

background Summarize the process of dealing with online problems. A large number of customers reported that the official website could not be accessed. After logging in to the database server, the database cpu soared to 1000%, and the business website could not be accessed. In the initial positioning, due to the database, it soared to 1000% so ...

The simple format of MySQL command granting user permission can be summarized as follows: grant permission on database object to user 1, grant ordinary data users have the right to query, insert, update and delete all table data in the database grant select on testdb.*to common_user@'%'; grant insert on testdb.*to common_user@'%'; grant updat ...