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Summary of several methods for removing duplicate data in SQL (window function for data deduplication)
catalogueMethod 1: distinctMethod 2: groupbyMethod 3: Window functionWhen using SQL to extract and analyze data, we often encounter scenarios where data is duplicated, requiring us to perform data deduplication and subsequent analysis.Taking the sales report of a certain e-commerce company as an example, we commonly use distinct or group by statements to deduplicate data...
Database Operation Tutorial 2023-05-12 12:13:26 -
Complete uninstallation and reinstallation of SQL Server
catalogueComplete uninstallation and reinstallation of SQL Server1. Control Panel Delete Names with&quo; SQL” Procedure for2...
Database Operation Tutorial 2023-05-12 12:13:17 -
Sql Server Management Implementation steps for Studio to connect to MySQL
targetGiven MySQL connection parameters (address and user), expect to use Microsoft; SqlServer Management Studio (hereinafter referred to as MSSSMS) connects to MySQL and directly queries or modifies data in MySQL in MSSSMS.realizationStep 1/4: Download and install MySqlConnector/ODBC at MySQL:: DownloadConnector/ODBCSelect the corresponding installation file based on the number of bits in the operating system...
Database Operation Tutorial 2023-05-12 12:13:01 -
Detailed explanation of SQL Server's memory management architecture
WindowsSQL Server 2.12...
Database Operation Tutorial 2023-05-12 12:11:27 -
SQL Detailed explanation of server's row level security
catalogue1 Preface2 Description3 Permissions4 Security note: Side channel attack5 Cross functional compatibility6 Example1 PrefaceRow level security allows you to control access to rows in database tables using group membership or execution context.Row level security (RLS) simplifies security design and coding in applications...
Database Operation Tutorial 2023-05-12 12:11:21 -
SQL Server's execution plan
catalogue1 Background2 Display and Save Execution Plan3 Display estimated execution plan4 Display actual execution plan5 Save execution plan in XML format6 Compare and analyze execution plans6.1 Comparison of execution plans6...
Database Operation Tutorial 2023-05-12 12:11:18 -
SQL Detailed explanation of sub queries for Server
catalogue1 Basic knowledge of sub queries2 Sub query rules3 Column names in qualified subqueries4 Multi layer nesting of subqueries5 Related sub queries6 Sub query typesummary1 Basic knowledge of sub queriesA subquery is a query nested within a SELECT, Insert, UPDATE, DELETE statement, or another subquery.You can use subqueries anywhere an expression is allowed...
Database Operation Tutorial 2023-05-12 12:11:06 -
SQL Server Single Table Data Query Example Explanation
catalogue1 Import data into SQL Server2 Example questions1. Query all information of all students2...
Database Operation Tutorial 2023-05-12 12:11:01 -
Zhihu's "515 Employee Day" is about to start, focusing on the work and life of new employees
On May 12th, it was announced that Zhihu will launch the "515 Employee Day" series of activities from May 15th to May 31st. It is understood that China's employed population is giving birth to a group of "new employees" who have received higher education, have professional experience and skills, and are mainly engaged in advanced manufacturing and the tertiary industry...
internet 2023-05-12 12:09:29 -
Apple Releases MacOSVentura13.4RC2 Update: Optimizing AppleNew
On May 12th, IT Home reported that Apple is targeting developers today,Released the second candidate RC version for macOSVentura13.4 (build number 22F63)A few days have passed since the last candidate version...
Intelligent devices 2023-05-12 11:11:53 -
Apple MacBook New Patent: Implementing Touch Pad, Palm Rest, and Screen Touch Interaction
IT Home reported on May 12th that according to the latest list published by the United States Trademark and Patent Office (USPTO),Apple has applied for a MacBook laptop with touch control.According to the patent description, this laptop not only has a touch screen, but also achieves tactile feedback in the palm rest area and touchpad position...
Intelligent devices 2023-05-12 11:11:53