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prefacePostgresSQL is a single example multi database. Usually, a database instance contains multiple tablespaces and databases. One tablespace can store multiple databases. In this relationship, one tablespace can contain multiple databases, but a database can only belong to one tablespace and cannot be stored across tablespaces. Table space i ...

Answer #11: what is the difference between char and varchar in MySQL1. Experimental scenarioGreatSQL 8.0.25 InnoDB2. Experimental test2.1 differencesparametercharvarcharIs the length variableFixed lengthLengthenstorage capacity 0 ~ 2550 ~ 65,5352.2 construction test tableCREATE TABLE vc (v VARCHAR(4), c CHAR(4));2.3 test without exceeding the s ...

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This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql preface This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql Dataset ...

Database installation Experimental environment Redhat8.3 Method 1: use the MySQL repository to install and deploy mysql 1, Add MySQL repository Add the MySQL Yum repository to the repository list of the system. This is a one-time operation that can be performed by installing the RPM provided by mysql. Follow these steps: Go to th ...

1. What is flink? Flink is a distributed open source computing framework for data stream processing and batch data processing, which supports both stream and batch applications. Because the SLAs (Service Level Agreement) provided by streaming and batching are completely different, streaming generally requires support for low latency, Exact ...

Building tables and inserting data -- Building tables -- Student table CREATE TABLE `Student`( `s_id` VARCHAR(20), `s_name` VARCHAR(20) NOT NULL DEFAULT '', `s_birth` VARCHAR(20) NOT NULL DEFAULT '', `s_sex` VARCHAR(10) NOT NULL DEFAULT '', PRIMARY KEY(`s_id`) ); -- Class Schedule Card CREATE TABLE `Course`( `c_id` VARCHAR(20), `c_name` VARCHAR ...

preface Continued [ORACLE] qualified expression of version 18c and its enhancement in version 21c At the end of the previous article, we talked about iterators. Because there are too many contents, they are put together with this article. In the iterator, in addition to the three iterators mentioned above (basic, index and sequence), it also ...

1. Process control structure 1.1 general In the actual development, we have to write thousands of lines of code. The order of the code is different, and the execution results will certainly be affected. Some codes can be executed only if they meet specific conditions, and some codes need to be executed repeatedly. How to reasonably plan these ...

Common cache algorithms:First in first out (FIFO) queue: first in first out. The data that enters first is eliminated first. Disadvantages: ignore the data access frequency and access times.Least recently used (LRU) : least recently used algorithm, that is, if the data has been accessed recently, the probability of being accessed in the future ...